Harlan Cobe

The Unofficial Simplified Guide to Chicago Style

A Practical Writing Manual for Authors, Editors, and Students

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Copyright © 2026 by Harlan Cobe 

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First Edition 2026 

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Table of Contents

Copyright Page

Chapter 1 - Introduction to Chicago Style

A Brief History of the Chicago Manual of Style

Core Principles and Philosophy of Chicago Style

Overview of the Two Citation Systems

Navigating the CMOS Structure Effectively

Practical Examples: Applying the Principles

Conclusion and Summary

Chapter 2 - Grammar Fundamentals

Subject-Verb Agreement

Pronoun Usage

Sentence Structure

Common Pitfalls and Chicago Style Solutions

Summary

Chapter 3 - Punctuation Rules

Commas: The Workhorse of Clarity

Semicolons: Stronger than a Comma, Weaker than a Period

Colons: Introducing and Emphasizing

Periods: The Full Stop

Dashes and Hyphens: Connecting and Separating

Parentheses: Containing Supplementary Material

Quotation Marks: Signal and Precision

Ellipses: Indicating Omission

Special Punctuation Cases in Chicago Style

Punctuation as a Guide

Chapter 4 - Capitalization and Spelling

The Invisible Order: Capitalization and Spelling

Capitalization of Proper Nouns and Derived Terms

Capitalization in Titles and Headings

Capitalization in Citations and Bibliographic Entries

Hyphenation and Compound Words

Preferred Spellings and Handling Variations

Consistency as the Ultimate Rule

Summary of Key Points

Chapter 5 - Numbers and Abbreviations

Numbers in Text: The General Rule

When to Break the General Rule

Dates, Decades, and Centuries

Percentages and Money

Abbreviations and Acronyms: General Principles

Forming Plurals and Possessives of Abbreviations

Scholarly Abbreviations

Abbreviations in Citations and Tables

Special Considerations for Numbers in Citations

Consistency and Flexibility: The Writer’s Judgment

Summary of Key Points

Chapter 6 - Quotations and Dialogue

Integrating Quotations Smoothly

Short Quotations vs. Block Quotations

Formatting Dialogue

Alterations to Quotations: Ellipses and Brackets

Citing Quotations Accurately

Summary of Key Points

Chapter 7 - Notes and Bibliography System: Basics

The Role of the Notes-Bibliography System

Understanding the Components: Notes and Bibliography

The Basic Structure of a Full Note

The Basic Structure of a Bibliography Entry

Shortened Notes for Subsequent Citations

When to Use Full Notes vs. Short Notes

Formatting Notes and Bibliographies

Practical Examples for Common Source Types

Using Notes for Commentary

Key Summary Points

Chapter 8 - Notes and Bibliography System: Books and Monographs

The Anatomy of a Book Citation: Core Elements

Single Author Books

First (full) note:

Shortened note (for subsequent citations):

Bibliography entry:

Multiple Authors

Two authors:

Three to ten authors:

Edited Volumes and Chapters within Books

Special Cases: Editions, Volumes, Series, and Translations

Editions:

Volumes:

Series:

Translations:

Ebooks and Online Books:

Consistency and Common Pitfalls

Summary of Key Points

Chapter 9 - Notes and Bibliography System: Periodicals

The Basic Journal Article Citation

Journal Articles in Print

Online Journal Articles: DOIs and URLs

Magazine Articles

Newspaper Articles

Special Issues and Supplements

Common Pitfalls and Best Practices

Summary

Chapter 10 - Notes and Bibliography System: Electronic Sources

The Foundation: Core Elements and Principles

Citing Websites, Blogs, and Social Media

Online Databases and Aggregators

Example for a journal article accessed via a database (no database name needed):

E-books and Digital Monographs

The Importance of Access Dates and Stable URLs/DOIs

Formatting Challenges and Practical Solutions

Summary of Key Points

Chapter 11 - Notes and Bibliography System: Other Sources

Introduction: Beyond Books and Periodicals

Citing Archival Materials and Manuscripts

Government Documents and Legal Sources

Interviews, Personal Communications, and Unpublished Works

Audiovisual and Multimedia Sources

Conclusion and Key Points

Chapter 12 - Author-Date System: Basics

Understanding the Author-Date System

The Purpose and Typical Use of the Author-Date System

The Two Core Components: In-Text Citations and Reference List

When to Choose the Author-Date System

Practical Examples: Building In-Text Citations and Reference List Entries

Common Pitfalls and How to Avoid Them

Integrating Author-Date Citations into Your Writing

Conclusion: Mastering the Basics

Chapter 13 - Author-Date System: In-text Citations

Understanding In-Text Citations in the Author-Date System

Parenthetical vs. Narrative Citations

Basic Format of Author-Date Citations

Citing Multiple Authors

Citing Multiple Works

Page Numbers and Specific References

Sources Without an Author

Sources Without a Date

Special Cases and Troubleshooting

Ensuring the Citation–Reference List Match

Summary of Key Points

Chapter 14 - Author-Date System: Reference List Entries

The General Format of a Reference List Entry

Core Elements and Punctuation

Creating Entries for Books

Creating Entries for Articles

Creating Entries for Electronic Sources

Alphabetization and Ordering Rules

Punctuation and Formatting Details

Practical Examples with Annotations

Summary of Key Points

Chapter 15 - Author-Date System: Variations and Special Cases

Citing Multiple Works by the Same Author

Handling Sources with Multiple Publication Dates

Classical, Religious, and Ancient Sources

Legal and Government Documents in Author-Date

Summary

Chapter 16 - Tables and Figures

The Purpose of Visuals in Scholarly and Professional Writing

Integrating Tables and Figures into Your Text

Numbering and Captioning Conventions

Sourcing and Citing Tables and Figures

Table Notes: General, Specific, and Probability

Formatting Tables for Clarity and Professionalism

Formatting Figures for Reproduction

Placement of Tables and Figures

Practical Examples

Summary of Key Points

Chapter 17 - Indexing and Documentation

The Purpose and Power of an Index

Creating Effective Indexes for Different Genres

Documentation Standards for Manuscripts

Tools and Techniques for Indexing

Cross-References and Subentries

Summary of Key Points

Chapter 18 - Manuscript Preparation and Formatting

Manuscript Preparation and Formatting

Formatting the Manuscript: Margins, Spacing, and Fonts

Front Matter Elements

Back Matter Elements

Page Numbering and Running Heads

Submitting Manuscripts to Publishers

Practical Examples of Layout

Summary

Chapter 19 - Editing and Proofreading Techniques

The Editing Spectrum: From Big Picture to Fine Details

Chicago Style as an Editor’s Compass

Proofreading Marks and Modern Practices

Collaborating with Authors and Editors

Practical Example: A Chicago-Style Copyedit

Chapter 20 - Common Mistakes and How to Avoid Them

Grammatical Errors That Plague Even Experienced Writers

Citation Pitfalls and How to Fix Them

Formatting and Punctuation Missteps

Strategies for Error-Free Writing

Chapter 21 - Chicago Style in Academic Writing

Applying Chicago Style in Theses and Dissertations

Discipline-Specific Variations

Balancing University Requirements with Chicago Style

Ethics and Plagiarism in Academic Writing

Summary

Chapter 22 - Chicago Style in Publishing

The Role of Chicago Style in Publishing

The Industry Standard for Books and Journals

Working with Copyeditors and Proofreaders

Adapting Style for Different Genres and Audiences

Digital Publishing Considerations

Summary of Key Points

Chapter 23 - Using Chicago Style with Digital Tools

Citation Management Software

Word Processor Features for Chicago Style Formatting

Collaborative Writing Tools and Style Guides

Automation and Its Limits in Style Compliance

Conclusion

Chapter 24 - Conclusion and Further Resources

Recap of Chicago Style Mastery

Key Takeaways for Authors, Editors, and Students

Recommended Resources: Books, Websites, and Courses

Companion Books and Guides:

Websites and Online Communities:

Courses and Formal Training:

Future Trends in Style Guides

Conclusion: Practice and Ongoing Learning

Chapter 1 - Introduction to Chicago Style

The Chicago Manual of Style is more than a rulebook; it is a living document that has guided writers, editors, and publishers through over a century of changing language, technology, and publishing practices. Often simply called “Chicago” or “CMOS,” this manual provides a comprehensive framework for grammar, usage, punctuation, manuscript preparation, and most famously, documentation of sources. For newcomers, the sheer size of the manual—over a thousand pages in its latest edition—can feel intimidating. Yet, once you understand its history, its underlying philosophy, and how it is organized, Chicago Style becomes an indispensable tool rather than an obstacle. This chapter lays the groundwork for that understanding, tracing the evolution of the CMOS, explaining its core principles, introducing its two citation systems, and showing you how to navigate the manual efficiently.

A Brief History of the Chicago Manual of Style

The roots of the Chicago Manual of Style stretch back to the late nineteenth century, when the University of Chicago Press was founded in 1890. As the press began publishing scholarly books and journals, editors recognized the need for a consistent house style to ensure uniformity across its growing catalog. In those early years, a single sheet of “style fundamentals” was pinned to a bulletin board in the press’s proofreading room. From that modest start, the first formal style sheet was compiled, and by 1906, the University of Chicago Press published the first edition of what was then titled Manual of Style: Being a Compilation of the Typographical Rules in Force at the University of Chicago Press, to Which Are Appended Specimens of Type in Use. It was a slim volume of about 200 pages, focused heavily on typography, typesetting, and proofreading marks—reflecting the concerns of a print-driven era.

Over the decades, the manual evolved to encompass far more than typography. As academic disciplines diversified and the publishing world expanded, each new edition responded to the changing landscape. The sixth edition (1969) saw a major expansion of the guidelines for citing sources, while the twelfth edition (1969) introduced the author-date system as an alternative to the traditional notes-bibliography method, acknowledging the needs of the sciences and social sciences. The thirteenth edition (1982) officially adopted the title The Chicago Manual of Style, reflecting its broader scope and influence beyond a single press.

The leap into the digital age came with the fifteenth edition (2003), which not only addressed electronic publishing and online sources but also marked the first time the manual was made available online by subscription. The sixteenth (2010) and seventeenth editions (2017) continued this trajectory, adding guidance for social media, e-books, digital rights, and the ever-expanding universe of online content. The current edition, the eighteenth, published in 2024, refines these digital-era concerns while reaffirming the manual’s commitment to clarity, consistency, and scholarly integrity. Each update is overseen by a dedicated editorial team at the University of Chicago Press, who consult with a wide range of experts to ensure the guidelines remain practical and authoritative. This history of regular revision is key: Chicago Style is not a static set of rules but a responsive, evolving resource that adapts to how we actually write and publish today.

Core Principles and Philosophy of Chicago Style

At its heart, the Chicago Manual of Style is built on a few foundational principles that distinguish it from other style guides. Understanding these principles helps you apply the rules with confidence, even when a specific situation is not explicitly covered.

First, Chicago Style prizes consistency above all else. The manual often states that a rule is less important than the consistent application of a chosen style within a document. For example, whether you use the serial comma (the comma before “and” in a list) or choose to omit it, the CMOS will support your decision—as long as you stick with it throughout your work. This flexibility is both a strength and a challenge; it empowers writers to make informed choices but also requires careful attention to detail.

Second, Chicago is comprehensive yet flexible. It aims to cover every conceivable editorial situation, from the correct placement of a semicolon to the citation of a live theater performance, but it does so with an acknowledgment that not every rule will fit every context. The manual provides a “default” recommendation while often offering alternatives for different fields or preferences. This makes it especially valuable for editors and writers who work across multiple disciplines, where a one-size-fits-all approach would be impractical.

Third, Chicago Style is fundamentally reader-centric. Its ultimate goal is to make the text as clear and accessible as possible for the reader. This principle guides everything from the preference for down-style capitalization (using fewer capital letters to avoid visual clutter) to the detailed rules for punctuation that aim to prevent ambiguity. When you find yourself debating a stylistic choice, asking “What serves the reader best?” will often lead you to the right answer.

Fourth, the CMOS serves as an authority without being authoritarian. It recognizes that language changes, that conventions vary by genre, and that many editorial decisions are matters of judgment rather than absolute correctness. The manual’s tone is advisory, not dictatorial, and it frequently explains the reasoning behind a guideline so that you can decide when to follow it and when a deviation might be justified.

Finally, the manual embodies the scholarly tradition of documentation. The systems of citation it offers are designed not only to give credit and avoid plagiarism but also to provide a robust trail of evidence that readers can follow. This commitment to traceable sources is one reason Chicago Style remains the standard for academic book publishing and many journals.

Overview of the Two Citation Systems

One of the most distinctive features of Chicago Style is its provision of two separate but equally valid citation systems: the Notes-Bibliography system (often abbreviated NB) and the Author-Date system. Choosing between them is your first major decision when adopting Chicago Style, and the choice hinges primarily on your discipline and the nature of your work.

The Notes-Bibliography system is the traditional method, widely used in the humanities—including history, literature, philosophy, and the arts. In this system, sources are cited in numbered footnotes or endnotes, which correspond to a superscript number in the text. Each note provides full or shortened bibliographic information, and a comprehensive bibliography at the end of the document lists all sources alphabetically. This system excels at accommodating a wide variety of source types, including archival materials, manuscripts, and other non-standard items that are common in humanities research. It also allows for discursive or explanatory notes, where the author can comment on a source or provide additional context without disrupting the main text.

A typical footnote in the Notes-Bibliography system looks like this:

> 1. Rebecca Skloot, The Immortal Life of Henrietta Lacks (New York: Crown, 2010), 87.

The corresponding bibliography entry would be:

> Skloot, Rebecca. The Immortal Life of Henrietta Lacks. New York: Crown, 2010.

The Author-Date system, on the other hand, is the preferred method in the sciences and social sciences, such as psychology, economics, political science, and many natural sciences. Here, sources are cited briefly in the text—usually in parentheses—by the author’s last name and the year of publication, with a page number if a specific passage is referenced. A reference list at the end of the document provides the full publication details for each in-text citation. This system keeps the text uncluttered and makes it easy for readers to see the currency of the research at a glance. It also aligns with the conventions of journals in these fields, where space is at a premium and extensive footnotes are uncommon.

An in-text citation in the Author-Date system looks like this:

> (Skloot 2010, 87)

And the reference list entry:

> Skloot, Rebecca. 2010. The Immortal Life of Henrietta Lacks. New York: Crown.

Both systems achieve the same goal—crediting sources and enabling readers to locate them—but they do so with different mechanics. The Notes-Bibliography system is more flexible for complex citations and allows for supplementary material in the notes, while the Author-Date system is more compact and immediately signals the date of the research. It is critical to choose one system and apply it consistently throughout a document; mixing the two can confuse readers and undermine your credibility. If you are writing for a publisher or a course, always check which system is required. The CMOS itself does not favor one over the other; it simply provides full guidelines for both, leaving the choice to the author or publisher.

Navigating the CMOS Structure Effectively

The Chicago Manual of Style is a large reference work, and learning to find what you need quickly is essential. The manual is organized into three main parts: the first covers the publishing process and manuscript preparation; the second, which forms the bulk of the book, addresses style and usage; and the third focuses on documentation and citation.

Part 1, “The Publishing Process,” deals with topics such as book design, typography, copyright, permissions, and the editorial workflow. For most students and writers, this section is less frequently consulted, but it becomes invaluable if you are preparing a manuscript for publication or self-publishing a work.

Part 2, “Style and Usage,” is the heart of the manual for day-to-day writing questions. It covers grammar, punctuation, spelling, word treatment, numbers, abbreviations, quotations, and all the mechanical details that make up a polished text. The chapters are arranged logically: you will find guidelines on commas in one chapter, on capitalization in another, and on the treatment of foreign words in yet another. The running heads and detailed subheadings make it relatively easy to flip to the right section once you know the manual’s organization.

Part 3, “Source Citations and Indexes,” is where the two citation systems are laid out in exhaustive detail. Chapter 14 covers the Notes-Bibliography system, while chapter 15 covers Author-Date. Each chapter begins with an overview and then presents a vast array of examples organized by source type—books, journal articles, websites, interviews, social media, and many others. This example-driven approach is one of the manual’s greatest strengths. Rather than memorizing rules, you can locate a model that matches your source and adapt it accordingly.

Beyond these three parts, the CMOS contains several appendices, a glossary of troublesome words and phrases, and a comprehensive bibliography of style and usage resources. However, the single most powerful tool for navigating the manual—whether in print or online—is the index. The index is extraordinarily detailed, running to dozens of pages in the print edition and functioning as a robust search tool in the online version. If you are unsure where to find a rule, the index is your first stop. For example, if you need to know whether to use “which” or “that,” look up “that; which” in the index, and you will be directed to the exact paragraph that explains the distinction.

The online edition of the CMOS, available by subscription, enhances navigation even further. It offers keyword searching, hyperlinked cross-references, and the ability to save notes and bookmarks. For many users, the online version has become the preferred way to access the manual, as it allows you to search across the entire text instantly and stay current with updates between print editions. The print edition, however, remains popular for those who prefer a tangible reference or who work in environments where screen use is limited.

To navigate the CMOS efficiently, adopt a strategy of targeted searching. Instead of reading the manual cover to cover, identify the specific issue you need to resolve. Use the index or the search function to go directly to the relevant paragraph. Read the rule and any accompanying examples, and note any cross-references to related sections. This habit will save you time and gradually build your familiarity with the manual’s structure.

Practical Examples: Applying the Principles

Let’s walk through a couple of common scenarios to see how the core principles and navigation strategies play out in practice.

Imagine you are editing a history paper and you need to cite a letter from an archive. You know the paper uses the Notes-Bibliography system. Unsure of the exact format, you turn to chapter 14. You could scan the section headings or use the index entry “letters (correspondence).” The manual directs you to paragraph 14.111, which provides this example:

> 2. James Oglethorpe to the Trustees, 13 January 1733, in The Colonial Records of the State of Georgia, ed. Allen D. Candler, vol. 1 (Atlanta: Franklin Printing and Publishing, 1904), 27.

You adapt this model to your source, confident that your citation will be correct.

Now suppose you are writing a psychology research article using the Author-Date system and need to cite a journal article with multiple authors. You go to chapter 15 and look for “journal articles, multiple authors.” You find that for a source with three authors, the in-text citation includes all three surnames (e.g., Smith, Jones, and Lee 2022, 45), but in the reference list, all authors are listed. For four or more authors, the in-text citation uses only the first author’s surname followed by “et al.” (e.g., Smith et al. 2022, 45). The reference list, however, still lists all authors. This rule balances conciseness in the text with completeness in the reference list—a clear example of the reader-centric philosophy.

These examples illustrate that the CMOS does not demand memorization; it provides models. By learning to locate and interpret those models, you can handle nearly any citation challenge.

Conclusion and Summary

The Chicago Manual of Style is a versatile and authoritative guide with a long history of adapting to the needs of writers, editors, and publishers. Since its origins as a simple style sheet at the University of Chicago Press, it has grown into a comprehensive reference that addresses everything from the finest points of punctuation to the complexities of citing digital media. Its regular updates ensure that it remains relevant in a rapidly changing communication landscape.

Central to Chicago Style are the principles of consistency, flexibility, and reader-centered clarity. The manual empowers you to make informed stylistic choices while providing a reliable default for nearly every situation. Its two distinct citation systems—Notes-Bibliography for the humanities and Author-Date for the sciences and social sciences—serve different academic and publishing needs, allowing the same core philosophy to support a wide range of disciplines.

Efficient use of the CMOS requires understanding its organization. The manual is divided into three parts covering the publishing process, style and usage, and documentation. The index and the online search function are your most valuable tools for pinpointing the exact rule or example you need. By approaching the manual as a resource to be consulted strategically, rather than a textbook to be memorized, you can integrate Chicago Style into your writing process without it becoming a burden.

As you continue through this book, you will delve deeper into the specifics of grammar, punctuation, formatting, and both citation systems. With the foundation laid in this chapter, you are now equipped to see Chicago Style not as a maze of arbitrary rules but as a logical, user-friendly system designed to help you communicate with precision and integrity.

Chapter 2 - Grammar Fundamentals

Grammar is the structural backbone of every sentence, paragraph, and manuscript. While The Chicago Manual of Style is best known for its citation systems and publishing guidelines, it devotes an entire chapter—chapter 5, “Grammar and Usage”—to the principles that underpin clear, correct writing. Chicago’s approach to grammar is not authoritarian; it recognizes that English is fluid and that many rules have exceptions or acceptable alternatives. The goal is always clarity and consistency. For modern writers and editors, mastering a handful of fundamental grammatical concepts eliminates the most common sources of confusion and strengthens every piece of writing, from a term paper to a published book.

This chapter explores the essential grammatical guidelines that Chicago Style users need most: subject-verb agreement, pronoun usage, and sentence structure. Along the way, we address frequent pitfalls and offer practical solutions that align with Chicago’s recommendations. By internalizing these fundamentals, you build a foundation that supports all other stylistic and formatting choices.

Subject-Verb Agreement

At its simplest, subject-verb agreement means that a singular subject takes a singular verb, and a plural subject takes a plural verb. Most writers grasp this instinctively: “The dog barks” versus “The dogs bark.” Problems arise when the subject-verb relationship is obscured by intervening words, tricky singulars, or compound subjects. Chicago provides straightforward guidance for these situations.

When a prepositional phrase separates the subject from the verb, the verb must agree with the subject, not the nearest noun. Write “The stack of books is on the table,” not “The stack of books are on the table,” because the subject is “stack,” not “books.” Similarly, phrases like “along with,” “as well as,” and “in addition to” do not change the number of the subject: “The professor, along with her students, attends the conference.” The singular subject “professor” still requires a singular verb.

Collective nouns—words such as “team,” “committee,” “audience,” “family,” and “staff”—can be especially tricky. In American English, Chicago generally treats them as singular when the group acts as a unit: “The committee has reached its decision.” However, when the members of the group are acting individually, a plural verb may be more natural: “The staff are divided in their opinions.” This notional agreement is acceptable, but Chicago advises consistency within a sentence or passage. If you start by treating “committee” as singular, don’t switch to a plural pronoun later in the same sentence unless you clearly signal the shift.

Indefinite pronouns are another frequent trouble spot. Words like “each,” “every,” “either,” “neither,” “one,” “nobody,” and “someone” are always singular. Thus: “Each of the candidates has submitted a statement.” “Everybody is welcome.” When “each” follows a plural subject, the verb remains plural because the subject is still the plural noun: “The students each have a unique perspective.” With “either…or” and “neither…nor,” the verb agrees with the nearer subject: “Neither the manager nor the employees are available,” but “Neither the employees nor the manager is available.” Chicago recommends placing the plural noun closer to the verb to avoid awkwardness whenever possible.

The word “number” can be singular or plural depending on the article that precedes it. “The number of errors is decreasing” (singular, because “number” is the subject and refers to a specific quantity). “A number of errors are still present” (plural, because “a number of” functions as an indefinite quantifier meaning “several”). Titles of works, names of organizations, and words used as words are always singular, even if they look plural: “The United Nations is headquartered in New York.” “The Canterbury Tales is a foundational work of English literature.” When a sentence begins with “there” or “here,” the true subject follows the verb, so the verb must agree with that subject: “There is a problem” versus “There are several problems.”

Pronoun Usage

Pronouns replace nouns, and their correct use depends on three factors: agreement with their antecedent in number and gender, proper case, and clarity of reference. Chicago’s guidelines on pronouns have evolved significantly in recent editions, reflecting broader changes in language and society.

The most notable shift concerns gender-neutral language. Traditionally, a generic singular antecedent like “a student” or “everyone” was paired with “he” or the awkward “he or she.” Chicago now accepts the singular “they” as a grammatically sound option when referring to a generic person or to a specific individual who prefers “they” as their pronoun. The seventeenth edition (2017) states that “singular they is widely used and accepted in formal writing,” though it cautions that some readers may still object. To maintain clarity, Chicago recommends trying to reword to a plural construction first (“All students must bring their laptops”) or eliminating the pronoun entirely. If those strategies fail, singular “they” is permissible: “Everyone should bring their own lunch.” When using singular “they,” the verb remains plural (“they are,” not “they is”), just as with the plural “you.” The key is to be consistent throughout a document and to consider the expectations of your audience or publisher.

Pronoun case errors often creep into compound constructions. Many people mistakenly say “Me and John went” or “The gift was for John and I.” The correct forms are “John and I went” (subjective case as the subject) and “The gift was for John and me” (objective case as the object of the preposition). To test, mentally remove the other person: you would never say “Me went” or “The gift was for I.” The same logic applies to “between you and me” (not “between you and I”). The relative pronouns “who” and “whom” follow a similar case distinction: “who” is subjective, “whom” is objective. In formal prose, Chicago still recommends using “whom” when it functions as an object: “The person to whom I spoke” or “Whom did you invite?” However, the manual acknowledges that “whom” is receding from informal usage, and in many contexts, recasting the sentence to avoid “whom” is the most elegant solution: “The person I spoke with” or “Who did you invite?” (acceptable in all but the most formal registers).

Reflexive pronouns (myself, yourself, himself, etc.) should only be used when the subject and object are the same entity (“I hurt myself”) or for emphasis (“I myself prefer tea”). They should never be used as a substitute for a simple personal pronoun: “Please contact John or myself” is incorrect; it should be “Please contact John or me.”

Relative pronouns introduce dependent clauses and must agree with their antecedents. The most common confusion involves “that” and “which.” Chicago follows the traditional distinction: use “that” for restrictive (essential) clauses that define or limit the noun, and use “which” for nonrestrictive (nonessential) clauses that add extra information. Restrictive clauses are not set off by commas; nonrestrictive clauses are. Compare: “The books that have torn covers need repair” (only the torn books need repair—the clause is essential to identify which books). “The books, which have torn covers, need repair” (all the books need repair, and by the way, they have torn covers—the clause is extra). In American English, “which” is not used for restrictive clauses, though British English sometimes permits it. Chicago is firm on this point for formal writing.

Sentence Structure

Even with perfect agreement and pronoun use, a sentence can fail if its structure is muddled. Three structural issues account for most grammatical breakdowns: faulty parallelism, misplaced modifiers, and run-on sentences.

Parallelism means that coordinate elements in a sentence should share the same grammatical form. This principle applies to items in a list, comparisons, and paired conjunctions. A nonparallel list—“She enjoys hiking, to swim, and biking”—forces the reader to stumble. The corrected version aligns the forms: “She enjoys hiking, swimming, and biking.” With correlative conjunctions such as “not only…but also,” “either…or,” and “both…and,” the structure following each part must match: “The report was not only thorough but also well-organized” (adjective paired with adjective), not “The report was not only thorough but also it was well-organized.” Parallelism also matters in comparisons: “The new software is faster than the old” is fine, but “The new software is faster than using the old” is lopsided; it should be “Using the new software is faster than using the old.”

Modifiers—words, phrases, or clauses that describe other elements—must be placed close to the word they modify. A dangling modifier occurs when the implied subject of the modifier is not the subject of the main clause: “Walking into the room, the chandelier sparkled” (the chandelier wasn’t walking). Correct it by supplying the logical subject: “Walking into the room, I noticed the sparkling chandelier.” A misplaced modifier simply sits too far from its intended target, creating ambiguity: “She served sandwiches to the children on paper plates” suggests the children are on paper plates. Reposition the modifier: “She served sandwiches on paper plates to the children.” Even a single word like “only” can cause confusion if misplaced: “I only read the first chapter” could mean I merely read it (as opposed to studying it) or I read only the first chapter and nothing else. For clarity, place “only” immediately before the word or phrase it limits: “I read only the first chapter.”

Run-on sentences and comma splices join independent clauses without proper punctuation. A comma splice uses a comma alone to connect two complete thoughts: “The experiment was a success, the results were published.” Chicago recommends fixing this by using a semicolon, a period, or a coordinating conjunction (and, but, or, nor, for, so, yet) after the comma. “The experiment was a success; the results were published” or “The experiment was a success, and the results were published.” A sentence fragment—an incomplete clause punctuated as a full sentence—can be used deliberately for stylistic emphasis, but in formal academic and professional writing, it is generally avoided unless the context clearly supports it. When in doubt, attach the fragment to a neighboring sentence or supply the missing subject and verb.

Voice—active versus passive—is a matter of style rather than a grammatical error, but it affects clarity. In active voice, the subject performs the action: “The researcher conducted the survey.” In passive voice, the subject receives the action: “The survey was conducted by the researcher.” Chicago does not prohibit the passive voice; it recognizes its usefulness when the agent is unknown, unimportant, or deliberately obscured (“The error was made in the calculations”). However, overusing the passive makes prose feel sluggish and evasive. Whenever possible, prefer the active voice for directness and energy.

The subjunctive mood, which expresses wishes, hypotheticals, or conditions contrary to fact, is another area where Chicago offers clear guidance. Use “were” instead of “was” in contrary-to-fact clauses: “If I were you, I would revise that section.” “I wish it were summer.” In formal writing, the subjunctive is also used after verbs of demanding, suggesting, or recommending: “The professor recommended that the student submit the paper early” (not “submits”). The subjunctive can feel archaic to some ears, but maintaining it in such contexts signals a polished, careful style.

Common Pitfalls and Chicago Style Solutions

Beyond the big structural rules, a host of smaller usage issues trip up even experienced writers. Chicago addresses many of these in its “Glossary of Problematic Words and Phrases” (section 5.250). Here we highlight a few that recur in academic and professional writing.

Confusing “affect” and “effect” is a perennial problem. Typically, “affect” is a verb meaning to influence (“The policy affects everyone”), and “effect” is a noun meaning a result (“The policy had a positive effect”). However, “effect” can also be a verb meaning to bring about (“The new manager effected many changes”), and “affect” can be a noun in psychology meaning an emotion, though that usage is rare outside the field. When in doubt, stick to the common verb/noun distinction.

The verbs “lie” and “lay” cause similar confusion. “Lie” is intransitive (does not take an object) and means to recline: “I lie down.” Its past tense is “lay,” which adds to the confusion: “Yesterday I lay down.” “Lay” is transitive (takes an object) and means to put or place: “I lay the book on the table.” Its past tense is “laid”: “I laid the book there.” Memorizing the principal parts helps: lie, lay, lain; lay, laid, laid.

The choice between “who” and “that” for people and animals is governed by nuance. Chicago prefers “who” (and “whom”) for human beings and for animals with a name or personality. “That” is acceptable for animals when they are being discussed generically or impersonally: “The dog that bit me” but “Our dog, who is a sweetheart, never bites.” For inanimate objects and concepts, always use “that” or “which.”

Quantifiers like “fewer” and “less,” “between” and “among,” “farther” and “further” follow traditional distinctions that Chicago upholds, though it acknowledges that real-world usage often blurs them. Use “fewer” for countable items (“fewer errors”) and “less” for mass quantities (“less time”). Use “between” for two entities and “among” for three or more, though “between” can be used for more than two when the relationship is reciprocal and individual (“trade between the four nations”). “Farther” typically refers to physical distance (“farther down the road”), while “further” is figurative or to a greater degree (“further discussion”). When the distinction is not clear-cut, Chicago advises using “further” for both.

A final note concerns split infinitives and ending sentences with prepositions. The old prohibitions against these constructions have long been discarded by Chicago. A split infinitive—inserting an adverb between “to” and the verb (“to boldly go”)—is perfectly acceptable when it sounds natural and avoids awkwardness. Ending a sentence with a preposition (“What are you talking about?”) is idiomatic English and often the most graceful option. Chicago’s only caution is to avoid a preposition at the end when it is redundant or leaves the sentence weak, but that is a matter of style, not grammar.

Throughout all these choices, Chicago’s supreme directive is consistency. If you decide to use the serial comma (which Chicago strongly recommends), use it throughout. If you treat “data” as a plural (“the data are”), maintain that treatment across the document. A consistent, well-edited manuscript signals professionalism and respect for the reader.

Summary

Solid grammar is the foundation of effective writing. The Chicago Manual of Style provides clear, flexible guidelines for the most common grammatical issues that writers face, from subject-verb agreement to pronoun usage and sentence structure. By paying careful attention to agreement—ensuring that subjects and verbs match in number, and that pronouns match their antecedents—you eliminate a major source of confusion. Thoughtful sentence structure, including parallelism, proper modifier placement, and correct punctuation of clauses, keeps your prose direct and readable. Chicago’s approach is not to impose rigid rules but to offer a trusted framework that helps you make informed decisions. When you master these fundamentals, you free yourself to focus on the content and argument of your writing, confident that your grammar supports rather than undermines your message.

Chapter 3 - Punctuation Rules

Punctuation is the invisible architecture of writing. It directs the reader’s eye, signals pauses and connections, and clarifies meaning without calling attention to itself. In the Chicago Manual of Style (CMOS), punctuation is treated not as an inflexible code but as a system of signals that, when applied consistently, guide the reader through even the most complex sentences. This chapter distills the essential punctuation rules from Chicago Style into practical, everyday guidance. By understanding the purpose and proper use of each mark, you can eliminate ambiguity, enhance readability, and present your work with professional polish.

Commas: The Workhorse of Clarity

The comma is the most frequently used—and frequently misused—punctuation mark. CMOS treats the comma as a tool for separating elements within a sentence, preventing misreading, and indicating natural pauses. The single most important rule in Chicago Style is to use the serial comma, also known as the Oxford comma.

The serial comma is the comma placed before the conjunction in a list of three or more items. Chicago strongly recommends its use because it removes ambiguity. Consider the difference: “I dedicate this book to my parents, Maya Angelou and Nelson Mandela.” Without the serial comma, the sentence suggests that Maya Angelou and Nelson Mandela are the parents. Adding the serial comma—“my parents, Maya Angelou, and Nelson Mandela”—makes it clear that the dedication is to three separate entities. In all lists, use a comma after each item except the last, before the conjunction.

Commas also set off introductory phrases and clauses. When a sentence begins with an adverb clause, a long prepositional phrase, or a participial phrase, a comma usually follows the introductory element to signal the start of the main clause. For example: “After reviewing the manuscript, the editor sent her comments.” Shorter introductory phrases (fewer than five words) may omit the comma if no misreading is possible, but consistency within a document is key.

Nonrestrictive clauses and phrases—those that add extra information but are not essential to the meaning of the sentence—are always set off by commas. Restrictive clauses, which define or limit the noun they modify, are not. Compare these two sentences: “The authors who submitted early received feedback promptly” (restrictive: only those who submitted early received feedback) and “The authors, who submitted early, received feedback promptly” (nonrestrictive: all authors submitted early and all received feedback). The commas change the meaning entirely. CMOS advises writers to test whether a clause can be removed without altering the core meaning; if so, it is nonrestrictive and requires commas.

Commas also separate independent clauses joined by a coordinating conjunction (and, but, or, nor, for, so, yet). If both clauses can stand alone as sentences, a comma precedes the conjunction: “The draft was complete, but the citations needed work.” Do not use a comma when a single subject has a compound predicate: “The editor reviewed the draft and returned it with notes.” Additionally, commas are used to set off parenthetical expressions, transitional adverbs (however, therefore, indeed), contrasting elements, and direct addresses. Mastering these basic comma rules will resolve the majority of punctuation errors in a manuscript.

Semicolons: Stronger than a Comma, Weaker than a Period

The semicolon signals a closer connection between clauses than a period would, yet a stronger separation than a comma. Its primary use is to join two closely related independent clauses without a coordinating conjunction. “The author revised the chapter; the editor approved the changes.” The semicolon implies a logical relationship that a period would make less explicit.

In complex lists where individual items contain internal commas, semicolons prevent confusion. For example: “The conference included speakers from Austin, Texas; Portland, Oregon; and Asheville, North Carolina.” Without semicolons, the city-state pairs would blur together. CMOS also permits the use of a semicolon before a conjunctive adverb (however, therefore, moreover) that joins two independent clauses: “The first draft was promising; however, the argument needed more evidence.” Notice that a comma follows the conjunctive adverb.

Avoid using a semicolon to join unequal grammatical elements, such as a clause to a phrase, or to introduce a list; a colon is the correct mark for those purposes. Semicolons always appear outside quotation marks and parentheses, and they are placed after closing quotation marks in dialogue or citations.

Colons: Introducing and Emphasizing

A colon is a mark of anticipation. It tells the reader that what follows will explain, illustrate, or expand upon the preceding clause. In Chicago Style, the text before a colon should be a complete independent clause. For instance: “The professor assigned three readings: a poem, a short story, and a historical essay.” A common error is placing a colon directly after a verb or preposition: “The three readings are: a poem, a short story, and an essay” is incorrect because “are” is not a complete clause. Either rephrase to create an independent clause or remove the colon.

Colons are also used to introduce block quotations, subtitles (as in “The Unofficial Simplified Guide to Chicago Style: A Practical Writing Manual”), and in scriptural or legal citations. When a colon introduces two or more complete sentences, the first word following the colon may be capitalized if the material is formal or if the sentences are presented as a series of complete statements. Chicago generally prefers lowercase after a colon when what follows is a single sentence or a fragment, but consistency is paramount.

Periods: The Full Stop

Periods mark the end of a declarative sentence. In Chicago Style, a single space follows a period at the end of a sentence—the days of double spacing are long gone. Periods are also used in abbreviations (e.g., “Dr.,” “U.S.,” “p.m.”), though many acronyms and initialisms drop the periods (NASA, NATO). CMOS advises that when an abbreviation ends a sentence, a single period serves both functions; do not double the period. In ellipses, the period interacts with the ellipsis points, a topic addressed later in this chapter.

Dashes and Hyphens: Connecting and Separating

Dashes and hyphens are distinct marks with distinct functions, yet they are often confused. The hyphen (-) joins words and separates syllables; the en dash (–) indicates ranges and connections; the em dash (—) sets off parenthetical or amplifying elements.

The em dash is the most dramatic punctuation in the writer’s toolkit. It can replace commas, parentheses, or colons to create a strong break in thought. Chicago Style uses em dashes without spaces on either side. For example: “The manuscript—despite its brilliance—was riddled with typos.” Em dashes can also introduce an explanatory or emphatic clause: “The editor offered one piece of advice—never skip the proofreading stage.” Avoid overusing em dashes; their power diminishes with frequency.

The en dash is longer than a hyphen but shorter than an em dash. Its primary role is to connect numbers, dates, and references to indicate a range: “pages 45–67,” “the 2020–2021 academic year,” “the London–Paris train.” It also connects compound adjectives where one element is itself a compound or an open compound: “post–World War II literature,” “a New York–based publisher.” In such cases, the en dash clarifies that the entire phrase modifies the noun, whereas a hyphen would incorrectly link only the adjacent words.

The hyphen’s main job is to link words into compound modifiers before a noun: “a well-researched paper,” “twentieth-century fiction.” When the compound adjective follows the noun, the hyphen is often omitted: “the paper is well researched.” Hyphens also join some prefixes (ex-husband, self-explanatory) and prevent misreading (re-cover vs. recover). Chicago provides an exhaustive hyphenation guide, but the governing principle is clarity. If a compound is unlikely to be misread, the hyphen may be unnecessary. In modern usage, many compounds evolve from hyphenated to closed (e.g., “email” instead of “e-mail”), and CMOS tracks these changes.

Parentheses: Containing Supplementary Material

Parentheses enclose material that is supplementary, explanatory, or digressive. The test is whether the sentence would remain grammatically complete and clear without the parenthetical content. If so, parentheses are appropriate. Punctuation placement depends on the context: if the parenthetical is part of a larger sentence, the closing punctuation goes outside the closing parenthesis (as here). If the entire sentence is enclosed in parentheses, the period belongs inside. (This is an example of a standalone parenthetical sentence.)

Parentheses are also used for in-text citations in the author-date system, for abbreviations after a full term, and for numbering items in a list. When nesting parentheses, Chicago uses square brackets for the inner level, though in most prose, restructuring the sentence is a better solution. Avoid overloading text with parentheses, which can fragment the reading experience; em dashes or commas often serve better.

Quotation Marks: Signal and Precision

Quotation marks enclose direct speech, quotations, and titles of short works. Chicago Style uses double quotation marks for standard quoted material and reserves single quotation marks for quotes within quotes. For example: The editor said, “The author told me, ‘I will revise the conclusion,’ and I agreed.” Commas and periods always go inside the closing quotation marks, a rule that applies in almost all American style guides. Semicolons, colons, question marks, and exclamation points, however, are placed outside the quotation marks unless they are part of the quoted material. For instance: Did the author really say, “The manuscript is perfect”? The question mark applies to the entire sentence, not the quotation, so it goes outside.

When quoting a passage of prose that runs five lines or more (or poetry of two or more lines), Chicago recommends setting it as a block quotation—indented, without quotation marks, and with the citation in parentheses after the final punctuation. This visual distinction signals to the reader that a longer extract is being reproduced.

Ellipses and brackets often appear in quoted material to indicate omissions or editorial insertions. These are discussed in the next section, but note that when a quotation is integrated into the text, any changes must be clearly marked.

Ellipses: Indicating Omission

An ellipsis is a series of three spaced periods ( . . . ) that signals omitted text within a quotation. Chicago Style dictates a space before and after each period, as well as a space before the first period and after the last, unless adjacent to quotation marks or other punctuation. When an omission occurs at the end of a sentence, a fourth period—the sentence period—precedes the ellipsis, with no space between the last word and the period. For example: “The author argued that the evidence was conclusive. . . . The committee agreed.”

In practical manuscript preparation, many writers use the precomposed ellipsis character (…) for simplicity, and Chicago accepts this with the caveat that the publisher may adjust spacing. The key is consistency. Ellipses are not used merely for a pause in thought in formal prose; that is the domain of the em dash. Reserve ellipses for quoted material and for indicating trailing off in dialogue or informal writing.

Special Punctuation Cases in Chicago Style

Beyond the core marks, several punctuation situations arise frequently in academic and professional writing. Apostrophes indicate possession and contractions. Chicago’s rule for singular possessive is to add ’s, even for names ending in s (e.g., “Kansas’s legislature”), unless tradition or euphony dictates otherwise (e.g., “Jesus’ teachings,” “for goodness’ sake”). Plural possessives add only an apostrophe after the s: “the authors’ manuscripts.”

Slashes are used sparingly in formal prose, primarily in “and/or” constructions or to indicate line breaks in poetry. Chicago advises that “and/or” is usually unnecessary; “or” alone often suffices. Brackets enclose editorial insertions within quoted material: “She [the editor] praised the structure.” They also enclose parenthetical material within parentheses, though such nesting should be avoided when possible.

The interaction of multiple punctuation marks at the end of a sentence can be tricky. When a sentence ends with an abbreviation that takes a period, no additional period is added. When a question mark or exclamation point coincides with a closing quotation mark, place the question mark inside if it belongs to the quoted material, outside if it applies to the surrounding sentence. In the rare event that both the quotation and the main sentence are questions, use a single question mark inside the quotation marks.

Chicago Style also addresses the use of punctuation in lists, vertical lists, and run-in lists. For run-in lists within a paragraph, items are separated by commas or semicolons, with a conjunction before the final item. For vertical lists, Chicago allows varied formatting: numbers or bullets, with or without punctuation after each item, depending on whether the items are complete sentences or fragments. The overriding rule is consistency and parallelism across all items.

Punctuation as a Guide

Every punctuation mark in Chicago Style serves the reader. A well-placed comma can prevent a misreading; an em dash can add emphasis without breaking the flow; a colon can promise a satisfying explanation. The goal is not to memorize every rule but to internalize the logic behind them. When you encounter a punctuation dilemma, ask yourself: Does this mark clarify meaning? Does it help the reader navigate the sentence? Does it maintain consistency with the rest of the document? If the answer is yes, you are applying Chicago Style effectively.

In summary, punctuation guides the reader through the text, acting as a silent conductor. Chicago Style has specific, well-reasoned rules for each punctuation mark, from the serial comma to the spacing of ellipses. Correct punctuation enhances readability and meaning, transforming a collection of words into a precise, professional piece of writing. By mastering these conventions, you equip yourself to communicate with authority and clarity in any academic, publishing, or digital context.

Chapter 4 - Capitalization and Spelling

The Invisible Order: Capitalization and Spelling

Capitalization and spelling might seem like the wallpaper of writing—unobtrusive, often unnoticed until something is out of place. Yet these elements are fundamental to the clarity and professionalism of any document. The Chicago Manual of Style (CMOS) devotes considerable attention to both, not to impose rigid dogma, but to offer a consistent framework that helps writers and editors present information in a predictable, reader-friendly way. This chapter distills the essential rules: how to capitalize titles, headings, and proper nouns; how to navigate the hyphenation of compound words; which spellings Chicago prefers; and how to apply these principles in citations and bibliographic entries.

Capitalization of Proper Nouns and Derived Terms

At its heart, capitalization in English signals the importance or uniqueness of a word. Proper nouns—the specific names of people, places, organizations, and things—are capitalized. Common nouns are not. Chicago follows this basic rule but provides detailed guidance for the inevitable gray areas.

Personal names and titles are capitalized when they directly precede an individual’s name as part of the formal title. For example: “President Lincoln” but “the president issued a statement.” When a title is used in apposition after a name or in place of the name, it is generally lowercased: “Abraham Lincoln, president of the United States” and “the president arrived.” Exceptions exist for titles of high distinction or when the context demands extra formality, such as “the Queen” in British contexts, but Chicago advises restraint and consistency.

Names of ethnic and national groups, languages, and religions are capitalized: “African American,” “Latin,” “Buddhism.” Terms derived from proper nouns often retain the capital, especially when they still carry a strong association with the source: “Machiavellian,” “Shakespearean.” However, when the connection has become generic through long usage, the word is lowercased: “pasteurize,” “french fries” (though Chicago notes that “French” in “French bread” may still be capitalized depending on context). The key is to consult a reliable dictionary—CMOS defers to Merriam-Webster’s Collegiate Dictionary as its primary lexical authority.

Geographical names and regions follow a similar logic. Capitalize recognized place-names: “Lake Michigan,” “the Midwest,” “the Deep South.” But generic descriptions are lowercased: “the lake,” “southern California” (where “southern” is a directional adjective, not part of a recognized region name). When compass directions are used to denote a cultural or political region, they are capitalized: “the West,” “the Eastern Seaboard.” Chicago warns against overcapitalizing; if you are simply indicating a direction, use lowercase: “drive east on Interstate 80.”

Organizational names, government agencies, and institutions are capitalized when given in full: “University of Chicago Press,” “Department of State.” Shortened or generic forms are lowercased: “the press,” “the department.” But some short forms retain capitalization when they stand for the complete name in a specific context: “the University” can be used in a publication about a particular institution to avoid repetition, provided the reference is clear. Similarly, movements and historical periods are capitalized when they are widely recognized as proper nouns: “the Renaissance,” “the Enlightenment,” “the Civil Rights Movement.” General descriptions are lowercased: “the baroque period,” “the civil rights era.”

Capitalization in Titles and Headings

One of the most frequently consulted sections of CMOS concerns the capitalization of titles of works and internal headings. Chicago offers two distinct styles: headline-style capitalization and sentence-style capitalization.

Headline-style capitalization, the traditional default, capitalizes the first and last words of the title or heading and all other major words. Articles (a, an, the), coordinating conjunctions (and, but, or, for, nor), and prepositions (regardless of length) are lowercased. However, CMOS notes that many editors choose to lowercase all prepositions, while some capitalize prepositions longer than four or five letters. The most important rule is to be consistent throughout a document. Examples: “A History of the English-Speaking Peoples,” “The Man Who Knew Too Much.” Notice that the first word after a colon in a title is always capitalized in headline style: “The Elements of Style: A Practical Guide.”

Sentence-style capitalization, on the other hand, capitalizes only the first word of the title or heading and any proper nouns or proper adjectives. This style is increasingly common in academic journals, especially in the sciences and social sciences, and it is the required format for reference lists in the Author-Date citation system. Examples: “Perspectives on the global economy,” “A study of French colonial architecture in Algeria.”

When preparing a manuscript, writers should verify which style their publisher, institution, or instructor requires. Chicago itself does not prescribe one over the other for general use but insists on consistency. In the Notes-Bibliography system, titles in notes and bibliographies are usually presented in headline style, while the Author-Date reference list uses sentence style. Internal headings within a document can follow either style, but they must be parallel in structure: if you capitalize the first heading headline-style, all headings of the same level should follow suit.

Capitalization in Citations and Bibliographic Entries

The application of capitalization rules becomes particularly critical in citations and bibliographies, where consistency is paramount. In the Notes-Bibliography system, the title of a book, article, or other work appears in headline style in both the notes and the bibliography. For example:

Note: 1. Laura J. Snyder, The Philosophical Breakfast Club: Four Remarkable Friends Who Transformed Science and Changed the World (New York: Broadway Books, 2011), 45.

Bibliography: Snyder, Laura J. The Philosophical Breakfast Club: Four Remarkable Friends Who Transformed Science and Changed the World. New York: Broadway Books, 2011.

Notice that the title is italicized for a book and set in headline style. For an article title, which is placed in quotation marks, the same headline style applies: “A New Perspective on Victorian Science.”

In the Author-Date system, the in-text citation is brief, but the reference list entry requires careful capitalization. Reference list entries use sentence-style capitalization for all titles, whether books, articles, or chapters. For example:

Reference list: Snyder, Laura J. 2011. The philosophical breakfast club: Four remarkable friends who transformed science and changed the world. New York: Broadway Books.

Here, only the first word of the title, the first word of the subtitle, and any proper nouns are capitalized. This difference between the two systems is a common source of confusion. A simple memory aid: Notes-Bibliography uses headline style for titles because the notes and bibliography are meant to mirror the formal presentation of the work; Author-Date uses sentence style to streamline the reference list and emphasize the date.

Journal titles, however, are always capitalized headline-style in both systems, and they are italicized: Journal of American History. Similarly, newspaper names are capitalized headline-style and italicized: The New York Times. When citing a chapter in an edited volume, the chapter title follows the capitalization style of the system (headline in NB, sentence in Author-Date), but the book title is always headline-style and italicized in both.

Hyphenation and Compound Words

Hyphenation is perhaps the most fluid aspect of English spelling, and Chicago acknowledges that no rule can cover every case. The guiding principle is to use hyphens to link words that function together as a single adjective before a noun, thereby preventing misreading. Thus, “a high-school student” is a student attending high school, while “a high school student” could be a school student who is under the influence of drugs. The hyphen clarifies the compound modifier.

CMOS divides compounds into three categories: open (two words, no hyphen, as in “high school”), hyphenated (“high-school”), and closed (one word, as in “homework”). The choice often depends on the function of the words in the sentence. Compound adjectives that precede the noun they modify are generally hyphenated: “a well-known author,” “a part-time job.” When the same compound follows the noun, the hyphen is often omitted: “the author is well known,” “she works part time.” However, some compounds are always hyphenated regardless of position, especially those that would be ambiguous or that contain a participle: “the decision was far-reaching,” “the report is up-to-date.”

Prefixes are a particular challenge. Chicago recommends hyphenating when a prefix stands before a proper noun (“un-American”), when the prefix ends and the root word begins with the same vowel and could cause confusion (“anti-inflammatory,” but “cooperate” is closed), and when the compound is a new or unusual formation (“post-9/11”). In many cases, common prefixes like “non,” “pre,” “re,” “sub,” and “over” are closed up: “nonprofit,” “predate,” “reenter,” “substandard,” “overachieve.” When in doubt, the dictionary is the final arbiter. Chicago’s preference is to minimize unnecessary hyphens and to close compounds when they have become familiar.

Numbers and fractions used as modifiers are hyphenated: “a twenty-one-gun salute,” “a two-thirds majority.” But a fraction used as a noun is open: “two thirds of the population.” Suspended hyphens are used to avoid repetition in a series: “first- and second-year students,” “a three- or four-year project.”

Compound nouns can be open, hyphenated, or closed depending on established usage. “Decision maker” is often open, while “decision-making” as an adjective or noun is hyphenated. “Healthcare” has largely closed up in American English, though some contexts still prefer “health care.” Chicago does not dictate a single form for every compound; instead, it directs writers to choose a current dictionary and follow its spellings consistently. The manual’s own hyphenation guide (section 7.89) provides an extensive table of compounds, but the best practice is to adopt a house style or dictionary and stick with it.

Preferred Spellings and Handling Variations

English is rich with variant spellings: “advisor” or “adviser,” “judgment” or “judgement,” “color” or “colour.” Chicago Style is grounded in American English and generally prefers the spellings given first in Merriam-Webster’s Collegiate Dictionary. Thus, “color,” “theater,” “center,” and “defense” are standard, while British spellings (“colour,” “theatre,” “centre,” “defence”) are reserved for quotations or works that specifically require British usage. For words with multiple acceptable American spellings, such as “advisor” (often preferred in academic contexts) and “adviser” (the more traditional form), Chicago advises picking one and using it consistently throughout a document.

The choice between “-ize” and “-ise” endings follows a similar pattern. American English prefers “-ize” in words like “organize,” “realize,” and “recognize.” Exceptions include words where the ending is part of the root, such as “advertise,” “compromise,” “exercise,” and “surprise.” Chicago provides a list of such exceptions (CMOS 7.33), but again, the dictionary is the safest guide.

For words of foreign origin, Chicago recommends retaining diacritical marks when they are part of the standard English spelling: “café,” “naïve,” “résumé.” However, when a word has been fully naturalized, the marks are often dropped: “debut,” “facade.” The trend is toward simplification, but context matters. In formal writing, many editors retain the acute accent in “résumé” to distinguish it from the verb “resume.” The manual advises consistency within a document and awareness of the audience’s expectations.

Plurals of nouns can also present spelling hurdles. Chicago’s default rule is to add “s” or “es” according to standard English patterns, but with proper nouns, things get trickier. The plural of a proper name is usually formed by adding “s” or “es” without an apostrophe: “the Smiths,” “the Joneses.” The apostrophe is reserved for possessive forms. For abbreviations, Chicago prefers adding a lowercase “s” without an apostrophe: “CDs,” “PDFs,” “1990s.” An apostrophe is used only to avoid confusion, as in “A’s” (the letter grade) or “do’s and don’ts.”

Consistency as the Ultimate Rule

Throughout this discussion, a single theme emerges: consistency is more important than any individual rule. Chicago Style does not exist to force every writer into a single mold; it provides a coherent system that, once adopted, makes a document easier to read and professionally credible. Whether you choose headline-style or sentence-style headings, whether you hyphenate “e-mail” or close it to “email” (Chicago now accepts the closed form), the critical step is to record your decisions and apply them uniformly.

Many publishers and institutions have their own house style sheets that supplement or override Chicago on specific points. As a writer or editor, you should create a style sheet for each project, noting the preferred spellings, capitalization patterns, and hyphenation choices. This simple tool prevents inconsistencies and saves time during the editing process. When in doubt, consult the latest edition of the dictionary you have adopted as authoritative, and if a spelling variant appears there, Chicago’s default is to use the first-listed form.

Summary of Key Points

- Consistent capitalization and spelling are essential for professional, polished writing. They signal attention to detail and respect for the reader.

- Chicago Style provides detailed, flexible rules for capitalizing proper nouns, titles, and headings. Headline-style capitalization is traditional for titles of works and notes-bibliography entries; sentence-style is standard for reference lists in the Author-Date system and is increasingly used in headings.

- Proper nouns, including names, places, organizations, and recognized historical periods, are capitalized. Generic terms and titles used alone are lowercased.

- Hyphenation of compound words follows patterns based on function: compound adjectives before a noun are usually hyphenated, while many compounds after a noun are open. Prefixes are often closed, but exceptions exist. Chicago relies on Merriam-Webster’s for compound spellings and encourages minimizing unnecessary hyphens.

- Preferred spellings in Chicago Style reflect standard American English. Variants are handled by choosing one form and applying it consistently throughout a document. A project style sheet is the writer’s best tool for maintaining this consistency.

Mastering capitalization and spelling according to Chicago may seem like a painstaking task, but it is ultimately an act of service to the reader. When these elements are handled correctly, they fade into the background, allowing the ideas and arguments to shine with clarity and authority.

Chapter 5 - Numbers and Abbreviations

Numbers in Text: The General Rule

One of the first questions writers ask about Chicago style is whether to spell out a number or use a numeral. The answer, like many things in The Chicago Manual of Style, depends on context and the type of writing. Chicago offers a flexible, principle-based system rather than a rigid formula. The overarching goal is readability and consistency.

The general rule in Chicago style for nontechnical writing—the kind found in most humanities, social sciences, and general nonfiction—is to spell out whole numbers from zero through one hundred, and also any round multiples of those numbers. Specifically, spell out zero through one hundred, plus numbers such as two hundred, three thousand, twenty thousand, and so on. Use numerals for all other numbers.

For example:

- There were thirty-seven people at the meeting.

- The manuscript contained 112 pages.

- She walked two hundred miles.

- The population reached 1,253.

This rule applies to cardinal numbers (one, two, three) and ordinal numbers (first, second, third) alike. So you would write the twenty-first century but the 121st attempt. The logic is that short, familiar words are easier on the reader’s eye, while longer or more complex numbers are more quickly grasped as numerals.

However, Chicago recognizes that many documents—especially scientific, technical, or statistical texts—benefit from a different approach. In those contexts, numerals are used for all numbers that are followed by a unit of measurement or that represent quantitative data. So even small numbers like 5 cm or 3 percent (in scientific text) appear as numerals. If you are writing a humanities paper, you might write five percent; in a social science report, 5% is common. Chicago allows this flexibility, but it stresses that once you choose a system, you must apply it consistently throughout a document.

When to Break the General Rule

Even within a single document, there are many situations where the general rule must give way to clarity. Chicago lists several specific cases where numerals are always used, regardless of the size of the number.

First, numbers that appear before a unit of measurement or an abbreviation of a unit are usually expressed as numerals: 6 feet, 12 mm, 3 kg. This is true even in nontechnical writing. The only exception is when the unit is not abbreviated and the number is small and round, such as a ten-mile hike. But if you write 10-mile hike, that is also acceptable. The key is to be consistent.

Second, numbers that are part of a statistical or mathematical discussion, percentages, decimals, and fractions always take numerals: a ratio of 4 to 1, only 3 percent, 0.25, multiply by 5. In nontechnical text, percentages up to one hundred may be spelled out (twenty percent), but numerals are also acceptable and often preferred for clarity.

Third, numbers that represent exact times, dates, ages, scores, points on a scale, and sums of money are typically given in numerals: at 3:00 p.m., the child was 2 years old, a score of 8 to 3, $5, rated 4 on a 5-point scale. When time is expressed in hours and minutes, use numerals with a colon (or a period in some British usage) and lowercase a.m. or p.m.: 10:45 a.m.. If the time is an even hour, you may omit the zeros: at 4 p.m. Chicago style does not use :00 unless you are listing times in a schedule where other times include minutes, for consistency.

Fourth, numbers that begin a sentence are always spelled out. If spelling out the number would be awkward, recast the sentence. Avoid starting a sentence with a numeral. So not “112 soldiers marched,” but “One hundred twelve soldiers marched” or, better, “A total of 112 soldiers marched.” This rule applies to all numbers, including years: “Nineteen eighty-four was the year the novel was published.”

Fifth, in a series or a range where some numbers would be spelled out and others would be numerals according to the general rule, you may express all the numbers in numerals for consistency. For instance, “The class sizes were 25, 112, and 9” is clearer than mixing “twenty-five, 112, and nine.” This is a practical application of the consistency principle.

Dates, Decades, and Centuries

Dates are almost always expressed in numerals in Chicago style. The month is spelled out when it stands alone or with a day, but when a full date is given, the day and year are numerals. The preferred format is month-day-year: October 5, 2025. In formal writing, avoid abbreviations for months (except in citations and tables, where standard abbreviations like Jan., Feb., etc., are acceptable). When the day is omitted, write October 2025 without a comma. If you use the international day-month-year format (5 October 2025), Chicago accepts it but notes that it is less common in American publications; consistency is again the watchword.

Years are always expressed in numerals, even at the start of a sentence (where you would either recast or spell out “Nineteen sixty-eight”). Do not abbreviate years with an apostrophe: the 1990s or the nineties, not the 1990’s unless you are indicating possession. For decades, you may write the 1960s or the sixties. The abbreviated form ’60s is acceptable in informal contexts but not in formal prose.

Centuries are spelled out and lowercased: the twentieth century, the eighth century. When used as an adjective before a noun, hyphenate: twentieth-century literature. Note that Chicago does not capitalize “century” unless it is part of a proper name (like a specific course title).

Percentages and Money

In nontechnical text, percentages are usually spelled out: twenty percent. The numeral-percent-sign form (20%) is standard in scientific and statistical writing. In humanities text, either form is acceptable, but you must use it consistently. When using the spelled-out form, write “percent” as one word. When using the symbol, there is no space between the numeral and the percent sign: 75%.

Sums of money are expressed in numerals when they are exact: $5.50, £10, €25. For large round numbers, you may combine numerals and words: $3 million, a $10 billion budget. This avoids long strings of zeros. When spelling out a currency amount, follow the same general rule for numbers: fifty dollars, two hundred pounds. However, if you have a mix of exact and round amounts in the same context, using numerals for all may be clearer.

Abbreviations and Acronyms: General Principles

Chicago style aims to keep the text readable by minimizing abbreviations in running prose. In formal writing, abbreviations like etc., i.e., and e.g. are confined to parentheses, footnotes, and tables; in the main text, they are best spelled out (and so forth, that is, for example). However, common abbreviations such as Mr., Mrs., Dr., and St. (for Saint) are perfectly acceptable in all contexts. The trend in modern editing is to omit periods from many abbreviations: US, UK, PhD, CEO, NASA. Chicago now recommends omitting periods in all-uppercase abbreviations (acronyms and initialisms) and in abbreviations that end with a capital letter. Lowercase abbreviations that could be confused with words (like a.m. and p.m.) retain periods. But if you prefer the traditional style with periods, be consistent.

An acronym is an abbreviation formed from the first letters of a series of words and pronounced as a word itself: NASA, NATO, scuba. An initialism is also formed from first letters but pronounced letter by letter: FBI, CEO, HTML. Chicago treats both similarly. The first time you introduce an acronym or initialism in your text (unless it is so common that it needs no introduction, like US or DNA), spell out the full term and put the abbreviation in parentheses: The National Endowment for the Humanities (NEH) announced new grants. Thereafter, use the abbreviation consistently. If the term appears only once or twice, it may be better to spell it out each time for clarity.

Forming Plurals and Possessives of Abbreviations

Plurals of abbreviations are formed by adding a lowercase s without an apostrophe: CDs, PhDs, 1990s, vols. The only exception is when the abbreviation has internal periods or is a single letter: M.A.’s (to avoid confusion with the word mas), x’s and y’s. For abbreviations that are already plural, like pp. for pages, no additional s is needed. Possessives follow the usual rule: add an apostrophe and s (CEO’s decision, NASA’s budget).

Scholarly Abbreviations

In academic writing, a host of Latin abbreviations are used in citations and parenthetical references. Chicago provides a comprehensive list, but the most common are:

- et al. (et alii, “and others”): for works with multiple authors. Use it in citations after the first author’s name, but in the bibliography (Notes-Bibliography system) all authors are usually listed.

- ibid. (ibidem, “in the same place”): used in earlier editions of Chicago to refer to the immediately preceding source. The 17th edition no longer recommends ibid.; instead, use a shortened citation. However, some disciplines still use it, so check your local guidelines.

- cf. (confer, “compare”): used to point the reader to a contrasting source.

- i.e. and e.g.: as noted, use them sparingly in text; they are fine in parentheses and notes.

When using these abbreviations, make sure they are lowercase and punctuated correctly. Et al. has a period only after al., because et is a full word.

Abbreviations in Citations and Tables

The context of citations and tables allows—and often demands—more extensive abbreviation than running text. In the Notes-Bibliography system, footnotes or endnotes and bibliographies use standard abbreviations for common bibliographic terms: ed. for edition or editor, trans. for translator, vol. for volume, no. for number, chap. for chapter, p. and pp. for page and pages. These are always lowercase and followed by a period. In the Author-Date system, in-text citations are already brief, so few additional abbreviations are needed, but reference lists use similar abbreviations.

Tables and figures have their own set of conventions. Because space is limited, abbreviations are expected. Chicago recommends that you spell out all abbreviations in a note below the table if there is any chance of ambiguity. For numbers in tables, numerals are almost always used, regardless of size, to align columns and facilitate comparison. If a table includes percentages, use the percent sign (%) consistently. Dates in tables may be abbreviated using standard three-letter month abbreviations (Jan., Feb., Mar., etc.) to save space. Money may be abbreviated with currency symbols.

Special Considerations for Numbers in Citations

Citations are another place where numbers follow specific rules. In the Notes-Bibliography system, page numbers are given in full: pp. 125–136. Use an en dash, not a hyphen, for ranges. For chapters and other divisions, use the appropriate abbreviation: chap. 4, vol. 2. In the Author-Date system, page numbers are preceded by a comma and a space: (Smith 2020, 45). When citing a source that is not paginated, such as an e-book, you may cite a chapter or section number: (Smith 2020, chap. 3) or use a locator like loc. for location.

In both systems, note numbers in the text are superscript arabic numerals. In the notes themselves, the number is full size, followed by a period, and then the citation. The first line of a note is indented, and subsequent lines are flush left. The bibliography, however, uses a hanging indent. Numbers in the bibliography are used for volume and edition numbers, series numbers, and dates.

When you cite a source with multiple volumes, the volume number is given in arabic numerals even if the original uses roman numerals: vol. 3, not vol. III. Page numbers are always arabic numerals. If a work uses roman numerals for front matter, you may retain them in the citation: pp. x–xv.

Consistency and Flexibility: The Writer’s Judgment

Throughout this chapter, the theme of consistency has recurred. Chicago style gives you a framework, but it also acknowledges that no set of rules can cover every situation. When you face a choice—whether to spell out percentages or use the symbol, whether to abbreviate a term or spell it out—the decision should be guided by your audience, the conventions of your discipline, and the need for clarity. Once you make a decision, record it on a style sheet and apply it uniformly.

A common pitfall is mixing number styles in the same sentence or paragraph. If you are discussing a range of values, don’t write “between 5 and twenty-five.” Instead, use either “between 5 and 25” or “between five and twenty-five.” Likewise, if you abbreviate a term, use that abbreviation every time it appears after the first full reference. Do not alternate between U.S. and United States arbitrarily.

Another point to remember is that the general rule for spelling out numbers works well for narrative prose, but in sections heavy with statistics, it is often better to shift to a numeral-only approach for all numbers. Chicago permits this, as long as the shift is intentional and the entire section follows the same logic. For example, a paragraph describing survey results might read: “Of the 250 respondents, 32% preferred option A, 45% option B, and 23% had no preference.” Even though 250 and 32 are below one hundred, they are presented as data points, so numerals are appropriate.

Summary of Key Points

- Chicago style’s general rule for nontechnical writing is to spell out whole numbers zero through one hundred and round multiples, and use numerals for others; however, many exceptions exist for clarity.

- Numerals are always used before units of measurement, in statistical contexts, for exact times and dates, and for money; sentences should not begin with a numeral.

- Dates follow month-day-year format with the year in numerals; centuries are spelled out and lowercased; decades may be spelled out or given as numerals without an apostrophe.

- Percentages may be spelled out in humanities text or expressed with the percent sign in scientific text; monetary amounts use numerals for exact sums and may combine words and numerals for large round numbers.

- Abbreviations should be used sparingly in formal prose; common abbreviations like Dr. and US are acceptable; introduce acronyms by spelling out the full term at first use, then use the abbreviation consistently.

- Plurals of abbreviations are formed by adding s without an apostrophe; possessives follow standard rules.

- Citations and tables have their own number and abbreviation conventions: numerals are standard in tables, and bibliographic abbreviations (ed., vol., p.) are used in notes and bibliographies.

- The overarching principles are clarity and consistency; when in doubt, choose the style that best serves the reader and apply it uniformly throughout the document.

Chapter 6 - Quotations and Dialogue

Quotations are the lifeblood of scholarly and professional writing. They provide evidence, lend authority, and allow you to engage directly with the words of other thinkers. Yet integrating someone else’s words into your own prose is not simply a matter of cutting and pasting. The Chicago Manual of Style offers a robust framework for presenting quotations that ensures your writing remains clear, accurate, and ethically sound. This chapter walks you through the essentials: how to weave short quotations into your text, when and how to set off longer passages as block quotations, how to format dialogue, how to indicate alterations responsibly, and—most critically—how to cite every quoted source with precision.

Integrating Quotations Smoothly

A quotation should never feel dropped into your text like a foreign object. It must be part of the grammatical and logical flow of your sentence. Chicago Style distinguishes between two methods of integration: run-in quotations and block quotations. Run-in quotations are those that remain within the normal lines of your paragraph, enclosed in double quotation marks. They are used for prose quotations of fewer than five lines (or roughly fewer than one hundred words) and for any length of quoted poetry when only a single line or part of a line is cited.

The key to seamless integration is the signal phrase. A signal phrase introduces the quotation and often names the author or source, establishing context. For example:

> As historian Jill Lepore argues, “The past is a foreign country, but it is not a foreign language.”

Alternatively, you can embed a quotation directly into your sentence structure:

> The committee’s report described the findings as “alarming and unprecedented.”

When integrating, pay careful attention to the punctuation that connects your words to the quoted material. If the quotation is introduced by a simple verb like says, writes, or claims, a comma usually precedes it. If the quotation is woven into the syntax of your sentence—for instance, as the object of a verb—no punctuation is needed before the opening quotation mark. Compare:

> The author notes, “Data integrity remains the project’s primary challenge.”

> The author describes data integrity as “the project’s primary challenge.”

The placement of other punctuation relative to closing quotation marks follows a consistent logic in Chicago Style. Periods and commas always go inside the quotation marks, regardless of whether they are part of the original quoted material. This is an American English convention and applies to both run-in quotations and dialogue. Semicolons, colons, question marks, and exclamation points, however, follow a different rule: they go inside the quotation marks only if they are part of the original quotation. Otherwise, they appear outside. Consider these examples:

> The instructions clearly state, “Close the lid tightly.”

> Did the instructions really say, “Close the lid tightly”?

> The author asks, “How can we reconcile these conflicting accounts?”

> I can’t believe she called the proposal “innovative”!

Such details may seem minute, but they contribute significantly to the professional polish of your manuscript. They also prevent ambiguity for your reader, who relies on these visual cues to navigate the boundaries between your voice and the voices of your sources.

Short Quotations vs. Block Quotations

When a prose quotation runs to five or more lines in your manuscript, Chicago Style dictates that it be formatted as a block quotation. For poetry, two or more lines of verse should be set as a block. The purpose of this visual distinction is to signal to the reader that a longer passage is being reproduced, and to avoid the clutter of quotation marks around a multi-sentence extract.

Block quotations are not enclosed in quotation marks. Instead, they are set off by starting on a new line and indenting the entire quotation from the left margin. The standard indentation is half an inch (or the same as your paragraph indentation), though some publishers may specify a different measurement. The block quotation retains the same line spacing as the surrounding text—usually double-spaced in academic manuscripts—and does not receive extra space above or below it. If the block quotation contains more than one paragraph, the first line of each subsequent paragraph is indented an additional quarter to half an inch to distinguish the paragraph