Chicago Style Title Case Rules Explained | TitleCasePro
Chicago Manual of Style title case capitalizes prepositions of 5+ letters but lowercases shorter ones. Complete CMOS 17 rules with examples.
Quick answer: Chicago title case capitalizes all major words plus prepositions of five or more letters (like About, Between, Through). It lowercases articles, coordinating conjunctions, and short prepositions of four letters or fewer.
Chicago style title case is defined by the Chicago Manual of Style (CMOS), 17th edition. It is the standard for book publishing, history, and humanities. Chicago uses a preposition-length rule: short prepositions (four letters or fewer) stay lowercase, but longer prepositions (five letters or more) are capitalized.
The defining rule: Prepositions of ≤ 4 letters are lowercase. Prepositions of 5+ letters are capitalized. This length-based approach is what most distinguishes Chicago from APA and MLA, which lowercase all prepositions regardless of length.
Chicago Quick Reference Cheat Sheet
The most commonly confused words in Chicago title case:
| Word | Chicago treatment | How other styles differ |
|---|---|---|
| about (5 letters) | Capitalize | APA / MLA: lowercase |
| between (7 letters) | Capitalize | APA / MLA: lowercase |
| with (4 letters) | lowercase | AP: Capitalize |
| to (infinitive) | lowercase | AP: Capitalize |
| is, are, be | Capitalize (verbs) | Same in all styles |
| First word after colon | Capitalize | Same in all styles |
Chicago Title Case Rules
According to CMOS 17:
- Capitalize the first and last word of the title and subtitle, always.
- Capitalize all major words: nouns, verbs, adjectives, adverbs, and pronouns.
- Lowercase articles: a, an, the (unless first or last word).
- Lowercase coordinating conjunctions: and, but, or, nor, for, so, yet.
- Lowercase prepositions of four letters or fewer: at, by, for, in, of, on, to, up, as, off, out, per, via, into (4), from (4), over (4), like (4), onto (4), down (4), with (4), upon (4).
- Capitalize prepositions of five or more letters: About (5), Above (5), After (5), Along (5), Among (5), Below (5), Since (5), Under (5), Until (5), While (5), Against (7), Around (6), Before (6), Behind (6), Beside (6), Between (7), Beyond (6), During (6), Except (6), Inside (6), Toward (6), Through (7), Within (6), Without (7).
- The infinitive “to” is a preposition in CMOS and stays lowercase.
- Hyphenated compounds: capitalize both elements, unless the second element is an article, preposition, or coordinating conjunction.
Chicago Title Case Examples
The preposition length rule in action
| Title | Note |
|---|---|
| A Guide to Writing About the Environment | to (2 letters) → lowercase; About (5 letters) → Capitalize |
| The Conflict Between Science and Religion | Between (7 letters) → Capitalize |
| Living Without Fear: A Practical Approach | Without (7 letters) → Capitalize |
| The Art of Writing in the Modern World | of (2), in (2), the → all lowercase |
⚠️ Common confusion: with has exactly 4 letters. Chicago’s rule is “4 letters or fewer” — so with is lowercase in Chicago. Don’t capitalize it.
Subtitle rule
The Art of Writing: A Complete Guide for Beginners — “A” after the colon is capitalized because it begins the subtitle.
Verb rule
Why Mindfulness Is Good for Students — Is → capitalize (verb). for → lowercase (preposition, 3 letters). Good → capitalize (adjective).
The 4-Letter Boundary: Quick Reference
| Letters | Treatment | Examples |
|---|---|---|
| 1–4 | Lowercase | at, by, for, in, of, on, to, up, via, off, into, from, over, like, with, upon, down, onto |
| 5+ | Capitalize | About, Above, After, Along, Among, Below, Since, Under, Until, Against, Around, Before, Between, Beyond, During, Through, Without |
Memory tip: Count the letters. With = 4 → lowercase. About = 5 → Capitalize. When in doubt, count.
Chicago vs. APA: The Key Difference
The most visible difference between Chicago and APA is how they handle medium and long prepositions.
| Preposition | APA | Chicago |
|---|---|---|
| about (5) | lowercase | Capitalize |
| between (7) | lowercase | Capitalize |
| through (7) | lowercase | Capitalize |
| without (7) | lowercase | Capitalize |
| with (4) | lowercase | lowercase |
| from (4) | lowercase | lowercase |
Same title, two styles:
- APA: A Comprehensive Study of the Conflict between Science and Religion
- Chicago: A Comprehensive Study of the Conflict Between Science and Religion
Only the capitalization of “Between” changes — everything else is identical. But this one word is the difference between correct and incorrect formatting in each style.
For a direct side-by-side comparison, use the APA vs Chicago comparison guide or the compare all styles tool.
Where Chicago Title Case Is Used
Chicago style is expected in:
- Book publishing across most genres (fiction, non-fiction, academic monographs)
- History and humanities journals
- Art, music, and film criticism
- General-audience magazines and essays
- US university presses (Chicago, Harvard, Oxford)
- Chicago-formatted theses and dissertations
Tip: Use the Chicago title capitalizer to apply CMOS 17 rules accurately, with a word-by-word breakdown explaining why each preposition was capitalized or lowercased.
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