Chicago Title Capitalization™

Headline Style vs Sentence Style in Chicago

The Chicago Manual of Style allows two approaches: headline-style and sentence-style. Headline-style, the default for most books and journals, capitalizes all major words. Sentence-style capitalizes only the first word, the first word after a colon, and proper nouns. This guide focuses on headline-style, which publishers use most often for book titles and chapter headings.

The Preposition Rule That Catches Everyone

In Chicago headline-style, every preposition stays lowercase—no exceptions for length. Unlike AP style, "through," "between," and "against" remain lowercase. So do "to" when it introduces an infinitive and all coordinating conjunctions. Capitalize:

• Major words: Nouns, pronouns, verbs, adjectives, adverbs, subordinating conjunctions
• First and last words: Always, regardless of part of speech
• Lowercase always: Articles ("a," "an," "the"), coordinating conjunctions ("and," "but," "or," etc.), all prepositions

Hyphenated Compounds and Subtitles

• Hyphenated phrases: Capitalize both elements if both are major words (e.g., "Twenty-First-Century")
• After a colon: Capitalize the first word of the subtitle
• Prefixes that stand alone: Capitalize the element after the hyphen when it's a major word

Examples in Chicago style:

• ✓ "From Colony to Nation: Trade and Politics in Early America"
• ✓ "War and Peace in the Age of Napoleon"
• ✓ "How to Publish Your First Novel"
• ✓ "Out of the Silent Planet and the Cosmic Trilogy"
• ✓ "Art History in the Digital Age: New Methods and Perspectives"

Chicago in Book Publishing

Chicago headline-style appears throughout:

• Trade and academic book titles
• Scholarly journals in history and the humanities
• Museum publications and gallery catalogs
• Literary and cultural studies monographs
• Chapter titles and running heads

Practical Quick-Reference

• Prepositions are always lowercase, including long ones
• Capitalize major parts of speech; lowercase articles and conjunctions
• First and last words get capitals
• Hyphenated compounds: capitalize both parts if both are major words
• Use the Chicago title tool above for automated formatting

Who Uses Chicago and What They Expect

The Chicago Manual of Style is the bible of book publishing. Trade houses, university presses, and academic journals in the humanities default to CMOS. If you're writing a monograph, a biography, or a cultural studies textbook, your editor will almost certainly expect Chicago headline-style capitalization. Literary magazines, museum catalogs, and historical societies often follow suit. This isn't a niche choice—it's the dominant style for long-form, book-length work in English.

Why headline-style over sentence-style? Books need visual hierarchy. Chapter titles and section headings should feel distinct from body text. Headline-style—with its capitalized major words—creates that distinction. Sentence-style, which capitalizes only the first word and proper nouns, reads more like a subtitle. Chicago allows both, but headline-style wins for most book titles and chapter headings.

Edge Cases: Hyphenated Words and "to" in Infinitives

Hyphenated compounds trip up even experienced writers. The rule: capitalize both elements if both are major words. "Twenty-First-Century" works because "Twenty," "First," and "Century" are all major words. "Self-Doubt" works. But "Re-evaluate"—the "evaluate" part is a major word, so capitalize it: "Re-Evaluate." Prefixes like "pre" and "post" that can't stand alone: capitalize the part after the hyphen only when it's a major word. "Pre-Raphaelite" (proper adjective) gets both; "co-author" might be treated differently by some editors. When in doubt, check CMOS 8.159.

And what about "to" when it introduces an infinitive? Chicago keeps it lowercase. "How to Publish Your First Novel"—that "to" is not a preposition here; it's part of the infinitive. Lowercase. Always.

Chicago vs AP: The Preposition Divide

If you're coming from journalism, Chicago will feel wrong at first. In AP, "through," "between," and "against" get capitalized (four or more letters). In Chicago, they stay lowercase. "War and Peace in the Age of Napoleon" is correct in Chicago. In AP you'd write "War and Peace In the Age of Napoleon"—no, wait, "In" has two letters in AP. Let me fix that: "in" stays lowercase in AP too. But "Through" and "Between" would be capitalized in AP. In Chicago they're always lowercase. The mental shift matters when you switch between audiences.

Common Chicago Mistakes

• Capitalizing long prepositions: "through," "between," "under," "during" are always lowercase in Chicago headline-style
• Over-capitalizing articles in the middle: "a," "an," "the" stay lowercase unless first or last
• Forgetting the first word after a colon: "Art History: New Methods"—capitalize "New"
• Inconsistent hyphenated compounds: pick a pattern and stick with it per CMOS rules

When to Use Chicago Headline-Style

Book titles, chapter titles, article titles in humanities journals, exhibition catalogs, and most scholarly monographs. If your publisher or professor has not specified a style, and you're in history, literature, or the arts, Chicago is a safe default. Copylime's Chicago title capitalization tool applies these rules automatically. Paste your title, get headline-style output. Copylime handles the preposition and hyphen rules so you don't have to.

CMOS in Detail: The Major-Word Standard

The Chicago Manual of Style doesn't give you a word-length rule like AP. Instead, it asks you to think about parts of speech. Major words—nouns, pronouns, verbs, adjectives, adverbs, and subordinating conjunctions like "because" and "although"—get capitalized. Minor words—articles, coordinating conjunctions, and all prepositions—stay lowercase. The catch: every preposition, no matter how long. "Through," "between," "under," "during," "throughout" are all lowercase in Chicago headline-style. That's the hill Chicago dies on. And editors will correct you if you capitalize them.

Subordinating vs Coordinating Conjunctions: A Quick Refresher

Subordinating conjunctions (because, although, when, if, unless) introduce dependent clauses and get capitalized in Chicago headline-style. Coordinating conjunctions (and, but, or, nor, for, so, yet) connect equal elements and stay lowercase. So "War and Peace in the Age of Napoleon" has lowercase "and" and "of." But "Why Nations Fail: The Origins of Power, Prosperity, and Poverty" has lowercase "and" in that list. The word "The" after the colon gets a capital because it's the first word of the subtitle. Got it? It takes a moment to internalize, but once you do, Chicago feels natural.

Who Uses Chicago and What They Expect

Trade publishers—the big houses in New York and London—default to Chicago. University presses do too. Academic journals in history, literary studies, and the arts typically follow CMOS. If you're writing a biography, a cultural studies monograph, or a textbook chapter, your editor will almost certainly expect Chicago headline-style. Museum catalogs, gallery publications, and historical society journals often use it. This isn't a niche choice. It's the dominant style for long-form, book-length work in English. Learn it once, use it everywhere in that world.

Edge Cases: Prefixes, Suffixes, and the Infinitive "to"

What about "to" when it's part of an infinitive? "How to Publish Your First Novel"—that "to" introduces the verb "publish." It's not a preposition here; it's part of the infinitive phrase. Chicago keeps it lowercase. Always. No exceptions. Prefixes like "re" and "pre" in hyphenated compounds: capitalize the element after the hyphen if it's a major word. "Re-Evaluate" works. "Pre-Raphaelite" works (and it's a proper adjective). "Co-author"—both elements might be capitalized in some treatments; CMOS 8.159 has the full detail. When in doubt, check the manual or ask your editor.

Chicago vs AP: Why the Preposition Rule Matters

If you switch between journalism and book publishing, you'll feel the whiplash. AP: "Study Finds Link Between Sleep and Memory." Chicago: "Study Finds Link between Sleep and Memory." One letter—the capital B in "Between"—marks the difference. AP capitalizes prepositions of four or more letters. Chicago lowercases every preposition. It sounds pedantic until you submit a manuscript to a university press with AP-style headlines. The copy editor will change every single one. Save yourself the revision.

Common Chicago Mistakes: A Checklist

• Capitalizing "through," "between," or "during"—they're prepositions, always lowercase in headline-style
• Forgetting the first word after a colon: "Art History: new methods" should capitalize "New"
• Over-capitalizing "a," "an," or "the" in the middle of a title
• Inconsistent hyphenated compounds: pick CMOS rules and apply them consistently
• Treating "to" as a preposition when it introduces an infinitive—it stays lowercase

Format titles in Chicago style.
The free Chicago title capitalization tool above applies headline-style rules to any text. Copylime makes it easy.

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