Headlines are the most-read part of almost everything you write. They appear in search results, in social-media previews, in newsletters, in tabs and bookmarks. Getting their capitalization wrong is the kind of mistake that doesn't trigger an error message — it just makes the brand look slightly amateurish to readers who notice these things. Plenty of readers notice.

This guide covers everything you need to capitalize headlines correctly, regardless of which style guide you follow. The principles are universal; the details differ between guides; we'll cover both.

The four headline-case rules everyone agrees on

Across AP, Chicago, APA, MLA, NYTimes, Wikipedia, Bluebook, and AMA, there are exactly four things everyone agrees on. If you do these four right, you'll be approximately right under any style guide.

  1. Capitalize the first word of the headline. No matter what type of word it is. The at the start of a headline is capitalized. And at the start is capitalized.
  2. Capitalize the last word of the headline. Same rule — first and last words are always major regardless of what they are. Where the Wild Things Are capitalizes Are because it's the last word.
  3. Capitalize all nouns, verbs, adjectives, adverbs, and pronouns. These are the "major" or "principal" parts of speech. They carry the meaning.
  4. Capitalize after a colon. If a colon introduces a subtitle or independent clause, the first word after the colon is capitalized. The Truth: It's Not What You Think.

If you stopped reading here and just did these four things, you'd be right most of the time. The other style guide rules are mostly about which "minor" words to lowercase — and those rules diverge.

The minor-word rules where styles diverge

The disagreement is about three categories of words.

Articles

A, an, the. Lowercase in every style guide unless they appear as the first or last word. This is unanimous.

Coordinating conjunctions

And, but, or, nor, for, yet, so. The seven coordinating conjunctions ("FANBOYS"). Lowercase in every major style guide unless first or last. Also unanimous.

Prepositions

This is where it gets complicated. Style guides disagree about which prepositions to lowercase based on their length:

  • AP: lowercase prepositions of three or fewer letters (at, by, in, of, on, to, up, as). Capitalize prepositions of four or more letters.
  • Chicago: lowercase all prepositions regardless of length. Through, against, between, without all stay lowercase.
  • APA (7th edition): capitalize all words of four or more letters even if they're prepositions or conjunctions. So With gets capitalized, but by stays lowercase.
  • MLA: lowercase all prepositions regardless of length, similar to Chicago.
  • NY Times: roughly AP's rule with some editorial nuance.
  • Wikipedia: lowercase prepositions of four or fewer letters.
  • Bluebook: lowercase prepositions of four or fewer letters.
  • AMA: similar to AP, lowercase prepositions of three or fewer letters.

The effect of these rule differences is most visible in headlines containing prepositions like with, over, through, against. Different style guides will produce different output for exactly the same input. None of them is wrong; they're different conventions.

The five words that trip everyone up

Here are the five words that cause the most headline-capitalization confusion in English. Knowing how each style handles them gives you a quick mental checklist.

1. Is and other forms of to be

It's a verb, but it's so short that many writers instinctively lowercase it. Every major style guide capitalizes it. The headline Inflation Is Cooling is correct; Inflation is Cooling is wrong.

2. With

A four-letter preposition. AP, NYTimes, APA, and AMA capitalize it. Chicago, MLA, Wikipedia, and Bluebook lowercase it. The Man with the Plan (Chicago/MLA) versus The Man With the Plan (AP/NYTimes) are both correct, just different.

3. Through

A seven-letter preposition. Most styles capitalize it (AP, APA, NYTimes, AMA all do because it's 4+ letters). Chicago and MLA lowercase it because they lowercase all prepositions.

4. Up

Two letters. Lowercase under most style guides because it's a short preposition — but if it's functioning as a verb particle (Look Up the Word), it should be capitalized because then it's part of the verb. Our case converter handles the common cases correctly, but ambiguous ones may need manual review.

5. That

A relative pronoun. Always capitalized in title case — pronouns are major words. The Book That Changed Everything capitalizes That.

The rules for hyphenated words

Hyphenated compounds are where headline capitalization gets genuinely complicated.

AP, Chicago (mostly), APA, NYTimes, Bluebook, AMA: Capitalize both parts of hyphenated compounds when both are major words. State-of-the-Art, Twenty-First-Century. The interior of, the, and remain lowercase.

Wikipedia: Don't capitalize the second part of hyphenated compounds in most cases. Mid-century, not Mid-Century.

Chicago, more specifically: Capitalize the first part always. Capitalize the second part if it's a noun, adjective, or proper noun. Lowercase the second part if it's a particle ("up", "off") or a numeric modifier in some cases.

Rule of thumb: when in doubt, capitalize both parts. It's the more common approach and looks more deliberate.

The rule for words after a colon

If a colon introduces a subtitle or independent clause, capitalize the first word that follows. The Truth: It's Not What You Think. On Writing: A Memoir of the Craft.

This is unanimous across all major style guides.

The rule for words in quotation marks

If a quoted phrase appears within a headline, you can usually treat the quoted text as its own unit and apply title-case to it, or you can preserve the original casing of the quoted text. The most readable convention is to treat the quoted phrase as a single unit and capitalize it the way the original source did. The Real Meaning of "be kind" if the original lowercase is meaningful; The Real Meaning of "Be Kind" if you're just citing a phrase.

The rule for brand names

Always preserve a brand's canonical capitalization. iPhone stays lowercase-i in any title case style. eBay stays lowercase-e. GraphQL stays G-L caps. PostgreSQL, JavaScript, USB-C, Wi-Fi — all stay in their canonical form regardless of the surrounding rule.

This is so common a source of error that our case converter ships with a 5,000-name proper-noun dictionary specifically to handle it.

The rule for acronyms

Always uppercase. NASA, FBI, NATO, NYC. Never Nasa or Fbi, even though some British publications do lowercase them in body copy. In headlines, all-uppercase is standard.

A practical checklist for any headline

When you're writing a headline and want to check capitalization, ask yourself this sequence:

  1. Is this the first or last word? Capitalize.
  2. Is this a known acronym (NASA, FBI)? Uppercase all letters.
  3. Is this a brand name with a specific style (iPhone, eBay)? Use the brand's canonical form.
  4. Is this a noun, verb, adjective, adverb, or pronoun? Capitalize.
  5. Is this an article (a, an, the) or coordinating conjunction (and, but, or, nor, for, yet, so)? Lowercase.
  6. Is this a preposition? Depends on your style guide:
    • AP/NYTimes/AMA: lowercase if 3 or fewer letters, capitalize if 4+
    • APA: capitalize if 4+ letters (even prepositions)
    • Chicago/MLA: lowercase all prepositions
    • Wikipedia/Bluebook: lowercase if 4 or fewer letters
  7. Does this follow a colon? Capitalize the first word after the colon.
  8. Is this part of a hyphenated compound? Capitalize each major part (with style-specific exceptions).

The shortcut: use a converter

Doing this manually for every headline is tedious. Our title-case converter applies the rules of any major style guide to any input, and explain mode tells you exactly which rule fired on each word. Switching between styles takes one click, so you can see what your headline looks like under AP versus Chicago and pick whichever fits your publication.

The mistake to avoid is "looks right to me" — there's no way to gut-check this consistently across hundreds of headlines a year. The mistake to embrace is having a documented style guide for your team and a tool that produces it predictably.