Title case rules: how AP, Chicago, and APA disagree

Title case sounds simple: capitalize the important words in a title. The trouble is deciding which words are important. Major style guides disagree on the details, which is why the same headline can be capitalized three different ways depending on whether it was edited by a newspaper, a book publisher, or an academic journal.

What every style agrees on

A few rules are close to universal:

• Capitalize the first and last word of the title, no matter what they are.
• Capitalize nouns, pronouns, verbs, adjectives, and adverbs.
• Lowercase the articles "a", "an", and "the" when they're in the middle of the title.
• Lowercase short coordinating conjunctions like "and", "but", and "or" in the middle.

The disagreements are mostly about prepositions and a few borderline words.

Chicago style

The Chicago Manual of Style, widely used in book publishing, lowercases all prepositions regardless of length, so "through", "between", and "without" stay lowercase in the middle of a title. It also lowercases "to" and "as" in most uses. Under Chicago, you'd write "A Walk through the Garden of Forgotten Things".

AP style

The Associated Press Stylebook, used by most American newspapers, capitalizes any word of four letters or more, including prepositions and conjunctions. Words of three letters or fewer are lowercased if they are articles, short conjunctions, or short prepositions. Under AP, you'd write "A Walk Through the Garden of Forgotten Things". Many news sites actually use sentence case for headlines, keeping AP title case for composition titles like books and films.

APA style

APA style, common in psychology and the social sciences, capitalizes words of four letters or more, like AP, and lowercases short conjunctions, articles, and short prepositions. APA also has its own rule for reference lists: titles of articles and books in references use sentence case, even though headings in the paper use title case.

Tricky cases

• Phrasal verbs: in "Set Up Your Account", "up" is part of the verb, not a preposition, so most styles capitalize it.
• Hyphenated compounds: Chicago generally capitalizes both parts ("Long-Term Plans"), with exceptions for prefixes and some articles or prepositions.
• Words after a colon: most styles capitalize the first word after a colon in a title, treating it as a new start.
• Acronyms and brand names: keep their established capitalization, like NASA, iPhone, or eBay, regardless of position.

Sentence case as an alternative

Because title case rules are fiddly, many organizations have switched to sentence case for headings: capitalize only the first word and proper nouns, as you would in a normal sentence. It's easier to apply consistently, and some readability research suggests it's slightly easier to scan. Many digital style guides, including several large technology companies' guidelines, recommend it for interface text and headings.

Using an automatic converter

Automatic title case can't know every exception. The case converter lowercases the most common short words (articles, short conjunctions, and short prepositions) in the middle of a title and capitalizes everything else, which produces a result close to most styles. For publication, give the result a final check against the specific style guide you're following, especially for longer prepositions, phrasal verbs, and acronyms.