Illustration of a book title with short connecting words highlighted in a different color

Text & writing

Title Case Rules: Which Words to Capitalize

Everyone agrees that title case capitalizes the “important” words, but style guides disagree about which small words stay lowercase. This guide covers the rules that are shared, the specific differences between AP, APA, Chicago, and MLA, and a worked example showing how one title comes out in each style.

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Rules nearly every style shares

  • Capitalize the first word of the title.
  • Capitalize nouns, pronouns, verbs, adjectives, and adverbs.
  • Keep articles (a, an, the) lowercase unless they begin the title.
  • Most styles also capitalize the last word, and the first word after a colon.

Where the major style guides differ

Chicago changed its rule in the 18th edition (2024): earlier editions lowercased all prepositions regardless of length. Check which edition your publisher or instructor expects.

Where the major style guides differ comparison
StylePrepositionsConjunctions
APLowercase if three letters or fewer; capitalize four letters or moreLowercase if three letters or fewer; capitalize four letters or more
APALowercase if three letters or fewer; capitalize four letters or moreLowercase short (three letters or fewer) conjunctions
Chicago (18th edition, 2024)Lowercase if four letters or fewer; capitalize five letters or moreLowercase the coordinating conjunctions and, but, for, or, nor
MLALowercase regardless of lengthLowercase coordinating conjunctions

One title, four styles

“Through” (seven letters) and “with” (four letters) are the words that change. AP and APA capitalize both because they have four or more letters; Chicago’s 18th edition capitalizes “Through” but keeps the four-letter “with” lowercase; MLA keeps every preposition lowercase.

One title, four styles comparison
StyleResult
APWalking Through the Forest With a Map
APAWalking Through the Forest With a Map
Chicago (18th edition)Walking Through the Forest with a Map
MLAWalking through the Forest with a Map

Automatic title case

Automatic converters, including the Looty Tools Case Converter, apply one general rule rather than a specific style guide. The Case Converter keeps articles, coordinating conjunctions, and prepositions of three letters or fewer lowercase unless they come first or last. For the example above it gives the AP/APA result, but for formal or published work you should check the output against the style guide you are required to use.

Title Case Rules FAQ

Do you capitalize “with” in a title?
It depends on the style. AP and APA capitalize “With” because it has four letters; Chicago (18th edition) and MLA keep it lowercase.
Should “is” be capitalized in title case?
Yes. “Is” is a verb, and verbs are capitalized in title case regardless of length.
Is the last word of a title always capitalized?
In most major styles, yes, even if it is a short word such as a preposition.
What changed in Chicago’s 18th edition?
Published in 2024, it capitalizes prepositions of five letters or more (such as “Through” or “About”); earlier editions lowercased all prepositions.
Does MLA capitalize long prepositions like “between”?
No. MLA lowercases prepositions regardless of length unless they are the first or last word of the title.

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