Every major style guide agrees on the core of title case: capitalize the first word, the last word, and all the major words in between. Where they split is the small stuff, specifically prepositions, conjunctions, and the word "to". That is the entire reason the same headline can be capitalized four different ways and all four be correct.
This page compares the eight title case styles you are most likely to need, shows exactly where they disagree, and helps you pick one.
Table of contents
Title Case Styles Compared at a Glance
The single biggest difference between the guides is how each one treats prepositions. Some lowercase every preposition no matter how long it is; others capitalize any preposition past a certain letter count.
| Style guide | Current edition | How it treats prepositions | Typical use |
|---|---|---|---|
| APA | 7th | Capitalize those with 4 or more letters | Social and behavioral sciences |
| AP | 2024-26 Stylebook | Capitalize those with 4 or more letters | News, blogs, marketing, PR |
| Chicago (CMOS) | 18th | Lowercase all, regardless of length | Books, humanities, business |
| MLA | 9th | Lowercase all, regardless of length | Humanities and literature |
| AMA | 11th | Lowercase those with 4 or fewer letters | Medical and scientific journals |
| Bluebook | 21st | Lowercase those with 4 or fewer letters | Legal writing and citations |
| New York Times | 5th | Lowercase short ones; capitalize when used adverbially | Journalism |
| Wikipedia | Manual of Style | Lowercase those with 4 or fewer letters | Wikipedia articles |
Take the headline "A Study on Sleep and Memory". Chicago and MLA lowercase "on" because it is a preposition. APA and AP also lowercase it, because "on" is only two letters. But change "on" to "about" and the guides split: APA and AP capitalize "About" at four or more letters, while Chicago and MLA still lowercase it. You can test any headline against a specific style with the title case converter.
The Rules Every Style Shares
Before the differences, it helps to know how much the guides actually agree on. In all eight styles above, you capitalize the first word of the title and the last word of the title regardless of what part of speech they are. You capitalize every noun, pronoun, verb, adjective, and adverb. That includes short verbs people often miss, such as "is", "be", and "do".
You also lowercase the three articles ("a", "an", "the") and the coordinating conjunctions ("and", "but", "or", "nor", "for", "so", "yet") when they fall in the middle of a title. Nearly every guide capitalizes the first word after a colon, treating the subtitle as a fresh start.
That shared core covers most of a typical headline. Two words cause the most trouble across guides: prepositions, and the "to" in an infinitive. For the second one, see is "to" capitalized in a title, and for prepositions generally, see title case prepositions and the 1 to 4 letter rule.
The Eight Major Title Case Styles
APA Style
APA, the American Psychological Association style, is the standard for research papers in the social and behavioral sciences. Capitalize all major words, plus any preposition or conjunction of four or more letters. In hyphenated words, capitalize the part after the hyphen as well ("Self-Report", not "Self-report"). The first word after a colon or dash is capitalized. Full rules and examples are in the APA title case rules guide.
AP Style
AP, the Associated Press Stylebook, is what most newsrooms, blogs, and marketing teams follow, which makes it the most common choice for general web writing. Capitalize all major words and any preposition or conjunction of four or more letters, so "With", "From", and "About" are capitalized but "on", "at", and "to" are not. AP also capitalizes both halves of a hyphenated word. See the AP title capitalization rules guide for the full breakdown.
Chicago Manual of Style
Chicago, now in its 18th edition, is the standard for books, long-form writing, humanities, and business. Capitalize nouns, pronouns, verbs, adverbs, and adjectives, along with subordinating conjunctions such as "because" and "although". Lowercase articles, the coordinating conjunctions, and every preposition regardless of length, which is the rule that most distinguishes Chicago from APA and AP. The Chicago title case rules guide covers the exceptions with copy-paste examples.
MLA Style
MLA, the Modern Language Association style, is used mainly in humanities and literature coursework. Its title rules line up closely with Chicago: capitalize all major words, and lowercase articles, prepositions of any length, and coordinating conjunctions unless one falls first or last in the title. See the complete MLA title case rules breakdown.
AMA Style
AMA, the American Medical Association Manual of Style, is used across medical and scientific publishing. Capitalize major words, and lowercase articles, coordinating conjunctions, and prepositions of four letters or fewer. For hyphenated compounds, capitalize both parts when the two words carry equal weight ("Cost-Benefit") but not when the second part is a prefix or suffix. In scientific names, capitalize the genus and lowercase the species, as in Dracaena trifasciata. The AMA title case rules guide has copy-paste examples for health writing.
Bluebook Style
The Bluebook, 21st edition, governs legal citations and briefs. Capitalize the first and last words and all major words, and lowercase articles, coordinating conjunctions, and prepositions of four letters or fewer. That means "with" and "from" stay lowercase in Bluebook while "Between" and "Through" are capitalized. For details see the Bluebook title case guide, and for UK legal writing see OSCOLA title capitalization.
New York Times Style
The New York Times Manual of Style and Usage is used in its own newsroom and widely imitated in journalism. Capitalize major words and lowercase articles, coordinating conjunctions, and short prepositions. Its distinctive rule is grammatical rather than mechanical: a short word like "on" or "up" gets capitalized when it functions as an adverb rather than a preposition, so "Carry On" takes a capital but "Notes on a Scandal" does not.
Wikipedia Style
Wikipedia's Manual of Style keeps article titles consistent across the encyclopedia. Capitalize nouns, pronouns, verbs, adverbs, adjectives, and subordinating conjunctions, and lowercase prepositions of four letters or fewer, so prepositions of five letters and up are capitalized. The Wikipedia title capitalization guide covers the edge cases.
Which Title Case Style Should You Use?
Often the choice is made for you. Submit to a journal, newspaper, publisher, or class and you will be told which guide to follow, or you are expected to use whatever is standard in that field. Academic work in the social sciences means APA, humanities means MLA, books and business mean Chicago, medicine means AMA, and law means Bluebook.
When nobody is dictating the style, which covers most blogging, marketing copy, and your own website, use AP. It is the most widely recognized, the simplest to apply, and the one your readers have seen most often. For press releases specifically, AP is effectively the default, and the press release headline capitalization guide shows how to apply it consistently.
Whatever you pick, the thing that matters most is applying it consistently across every title on the site or document. Mixing two guides produces headlines that look almost right and read as careless. Common slip-ups are collected in common title case mistakes.
Also worth knowing: title case is not always the right format at all. News headlines, app interfaces, and email subject lines have largely moved to sentence case. See title case vs sentence case for when to use each, and for biology and life sciences the CSE title case guide covers that field's conventions.
To skip the rules entirely, paste your headline into the title capitalization tool and pick a style.
