APA vs Chicago Title Capitalization

APA and Chicago settle prepositions the same way — by counting letters — and then put the line in different places. APA capitalises a preposition once it reaches four letters. Chicago waits for five. That one-letter gap is the entire disagreement between the two styles, and it lives in a short, memorable band of words: with, from, into, over, onto, upon, past, near, next, like, down and than are capitalised by APA and lowercase in Chicago. Below four letters and above five, the two styles agree word for word.

APA Title Capitalization

APA 7 (§6.17) capitalizes major words — nouns, verbs, adjectives, adverbs, pronouns — and every word of four letters or more, including prepositions such as "With," "From," "About," and "Between." Only articles and conjunctions or prepositions of three letters or fewer are lowercase, and never as the first or last word.

Used in:Psychology, Social Sciences, Education, Business

APA rules

• Capitalise all major words (nouns, verbs including linking verbs, adjectives, adverbs, pronouns)
• Capitalise every word of four letters or more — including prepositions: "With", "From", "About", "Between", "Through", "Without"
• Lowercase: articles (a, an, the)
• Lowercase: conjunctions of three letters or fewer (and, but, or, nor, for, so, yet)
• Lowercase: prepositions of three letters or fewer (of, on, in, to, at, by, up, as, via, off, out, per)
• Always capitalise first and last word
• Always capitalise the word after a colon

Chicago Title Capitalization

CMOS 17 capitalises all major words. Short prepositions (≤4 chars) are lowercase, but longer ones like "About" and "Between" are capitalised.

Used in:Books, Publishing, History, Arts & Humanities

Chicago rules

• Capitalise all major words
• Lowercase: articles (a, an, the)
• Lowercase: coordinating conjunctions (FANBOYS)
• Lowercase: prepositions ≤4 letters (at, by, for, in, of, on, to)
• Capitalise: prepositions ≥5 letters (About, Above, Between…)
• Always capitalise first and last word
• Capitalise both parts of a hyphenated compound

Where APA and Chicago Actually Disagree

The ten titles below are run through the same capitalisation engine that powers the tool on this site — not written out by hand, so they cannot drift from what you get when you paste a title in. Each set is chosen for its own pair, built around the words nearest that pair's boundary: three-letter prepositions (via, off, out, per), four-letter ones (with, from, into, over, next, like), long ones (about, during, through, without), an infinitive "to", a colon and a hyphenated compound. 7 of the 10 titles come out differently; 3 are identical. Differing rows are marked.

One Letter Apart

Both styles ask the same question of a preposition — how long is it? — and both capitalise it once it is long enough. They simply set "long enough" one letter apart. APA's threshold is four: Section 6.17 defines minor words as articles plus conjunctions and prepositions that are short, meaning three letters or fewer, and states that all words of four letters or more are major. Chicago's threshold is five: its lowercase set runs to four-letter prepositions, and a preposition of five letters or more is capitalised.

Everything the two styles do differently sits in that single-letter band, and in practice twelve everyday prepositions fill it. Each is a capital in APA and a lowercase in Chicago: with, from, into, over, onto, upon, past, near, next, like, down and than. A handful of rarer four-letter prepositions behave the same way — amid, atop, plus, unto, till — but if a title contains none of these words, the two styles return the same string.

The engine bears that out. Stepping Into the Unknown is APA; Stepping into the Unknown is Chicago. The Road Over the Mountain against The Road over the Mountain. Notes From a Small Island against Notes from a Small Island. In every case one four-letter word moves and nothing else does.

Above the band they converge again, because five letters clears both thresholds. About, above, across, after, among, before, between, beyond, during, through, under, until and without are capitalised by APA and by Chicago alike, which is why A Guide to Writing About the World is identical in both. A title can even show the convergence and the divergence at once: Letters From Home During Wartime in APA and Letters from Home During Wartime in Chicago differ on the four-letter from and agree on the six-letter During.

Below the band they converge for a second reason. At, by, in, of, on, to, up, via, off, out and per are inside both lowercase sets, as are the three articles and the coordinating conjunctions. Chicago also has an explicit rule keeping the infinitive to down, and APA gets there anyway because to is two letters — so How to Build a Habit That Lasts comes out the same in each, by two different routes.

Why the Line Sits Where It Does

The four-letter line is a consistency device. APA governs a literature in which titles run long, clause-heavy and full of prepositional phrases, and the value of the rule is that two authors handed the same title reach the same capitalisation without negotiating. Counting letters is the least arguable test available; nobody disputes whether into has four of them, whereas people genuinely disagree about whether than is functioning as a preposition or a conjunction in a given title. APA buys agreement by refusing to ask.

Chicago's extra letter is a typographic judgement. CMOS editors work on jackets, title pages and running heads, where a title is a designed object. Their view is that the very smallest connectives genuinely recede on the page and should stay down, while a word with real width starts to look like a mistake when it is lowercase. Where APA and Chicago disagree about that is precisely at four letters — long enough that APA reads it as a word with weight, short enough that Chicago still reads it as a connective.

Neither line is more principled than the other, and there is no argument that settles it. The practical consequence is small and easy to act on: converting a title between APA and Chicago never requires re-reading it. Scan for the twelve four-letter prepositions and change only those.

Hyphenated Compounds: The Rule Only Chicago Writes Down

CMOS §8.157 gives Chicago a rule APA has no equivalent of: in a hyphenated compound, capitalise both elements — unless the second element is an article, a preposition or a coordinating conjunction. Chicago is deciding about the compound as a unit, and the exception is deliberately narrow.

What makes this less dramatic than it sounds is that Chicago applies its own four-letter line inside the hyphen, and APA applies its four-letter line there too — so the compound behaves exactly like the standalone words. Where the second element is a long preposition, both capitalise: The Follow-Through of a Promise and A Walk-Through of the Writing Process are identical in APA and Chicago, because through clears both thresholds. Where the second element is very short, both lowercase: A Trade-off Between Speed and Cost, A Stand-in for the Star and A Knock-on Effect are the same in each.

The split reappears only in the same four-letter band as everywhere else. The hand-over of power is The Hand-Over of Power in APA and The Hand-over of Power in Chicago; a run-down of the news splits into A Run-Down of the News and A Run-down of the News. And where the second element is not a minor word at all — Self-Report, Well-Being — both styles capitalise both halves, since §8.157's exception never fires and APA sees a four-letter-plus major word.

Position Beats Length in Both Styles

The four-letter band only matters mid-title. Both styles capitalise the first word, the last word and the first word after a colon no matter what part of speech it is or how short it is, and that override runs ahead of every length test. So over the rainbow is Over the Rainbow in APA and in Chicago; into the woods is Into the Woods in both; and the world we walked into ends on a capital in both as The World We Walked Into.

This is why short titles so rarely expose the difference between the two styles. A three-word title has only one mid-title slot, and the odds that a four-letter preposition lands in it are low. The divergence emerges as titles get longer and more prepositional phrases appear in the middle — which is exactly the shape of an academic title, and part of why the choice feels more consequential in a journal than on a book cover.

The practical version of this: when you are checking a converted title, ignore the first and last words entirely. Any disagreement between APA and Chicago is somewhere between them.

Which One Should You Use

Follow the requirement, not the aesthetics. If you are submitting to a psychology, education, nursing, social science or business journal, use APA; its four-letter line is not a preference there, it is a submission condition, and the reference-list conventions that come with it matter far more than the title does. If you are writing a book, a monograph, a history article or long-form non-fiction, use Chicago, because publishers and their copyeditors will expect §8.157 and the five-letter threshold and will correct a capitalised With back down.

For a personal blog, a portfolio or anything with no house style, either is defensible and the difference is invisible to almost every reader. If you want a tiebreaker: a title capitalised in Chicago is also correct Bluebook in nearly every case, and one capitalised in APA is also correct AP in every case — so pick whichever second style you are more likely to need.

See Both Styles Applied to Your Title

The fastest way to understand the difference between APA and Chicago is to enter your own title and see both results. Use the style comparison tool to see your title in all nine styles simultaneously, including both APA and Chicago. Or open either style guide, each of which has the capitalizer built in:

• APA title capitalization rules and converter
• Chicago title capitalization rules and converter

Related Comparisons

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• APA vs AP title capitalization
• Chicago vs MLA title capitalization

Frequently Asked Questions

What is the difference between APA and Chicago title case?

Both capitalize the long prepositions — "About," "Between," "Through," and "Without" take a capital in each style. They split at four letters: Chicago lowercases prepositions of four or fewer letters, so "with," "from," and "into" stay down, while APA capitalizes every word of four letters or more. "Living With Uncertainty" in APA is "Living with Uncertainty" in Chicago. Enter a title in the comparison tool to see both results instantly.

Does APA capitalize more words than Chicago?

Yes, slightly. APA capitalizes every word of four letters or more, so four-letter prepositions like "with," "from," "into," and "over" get capitals that Chicago withholds. On titles that use only long or only very short prepositions, the two styles agree.

How does APA treat short words in titles?

APA lowercases articles (a, an, the), coordinating conjunctions (and, but, or, nor, for, so, yet), and prepositions of three letters or fewer (of, in, on, to, at, by, up, via) when they appear in the middle of a title. Anything four letters or longer is capitalized.

How does Chicago treat short prepositions in titles?

Chicago lowercases prepositions of four or fewer letters: at, by, for, in, of, on, to, up, via, from, into, like, onto, over, down, than, with. These account for the most commonly used prepositions in English titles.

Should I use APA or Chicago for academic writing?

It depends on the field. APA is standard for psychology, education, sociology, and behavioral sciences. Chicago is standard for history, humanities, and general book publishing. If your field is ambiguous, check your specific journal's or institution's style guide.

Should I use APA or Chicago for book titles?

Chicago is the standard for most book publishing. APA is used for book titles within APA-formatted references and papers. If you are publishing a book, follow Chicago unless your publisher specifies otherwise.

Can I convert the same title in both APA and Chicago style?

Yes. The Compare Styles tool shows your title in all 9 styles simultaneously — including both APA and Chicago in the same table.

Can I compare APA and Chicago title case side by side?

Yes. Enter any title in the comparison tool at /compare and both APA and Chicago results appear on the same screen.