englishusage.infoUsage · Phrases · Writing
Writing & StyleWord guide

Is “Inside” Capitalized in a Title?

Inside can function as a preposition, adverb, adjective, or noun. APA, Chicago 18, and MLA do not use one universal “small word” rule; capitalization depends on style and, where the word has multiple grammatical roles, on its function in the title.

ReviewedEvidence6 sourcesSectionWriting & Style
Quick answer

APA: capitalize internally. Chicago 18: capitalize internally. MLA: lowercase it as a preposition; capitalize it in major-word roles such as adverb/adjective/noun.

Key details

APA 7capitalize internally.
Chicago 18capitalize internally.
MLA 9lowercase it as a preposition; capitalize it in major-word roles such as adverb/adjective/noun.
TermsInside
Word Classa preposition, adverb, adjective, or noun

Important caveats

Automation boundary

Automatic treatment is appropriate only when the grammatical role is clear. If part of speech or embedded-title structure is unresolved, do not guess.

Grammar Boundary

Cambridge documents Inside as a preposition, adverb, adjective, or noun. When a style treats prepositions differently from conjunctions/adverbs, the grammatical role matters.

Further guidance

Quick rule

APA: capitalize internally.

Chicago 18: capitalize internally.

MLA: lowercase it as a preposition; capitalize it in major-word roles such as adverb/adjective/noun.

Sources and evidence

Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.

  1. Title case capitalization (opens in a new tab)American Psychological Association · APA title-case rules
  2. What's New in the 18th Edition (opens in a new tab)The Chicago Manual of Style / University of Chicago Press · Chicago 18 title-case terminology and five-letter-preposition change
  3. Headlines and Titles of Works — Chicago Q&A (opens in a new tab)The Chicago Manual of Style / University of Chicago Press · Chicago title-case rules and current-edition updates
  4. How should I capitalize the title of a handout? (opens in a new tab)MLA Style Center / Modern Language Association · MLA title-style capitalization
  5. In MLA style, should any part of a two-word preposition be capitalized in a title? (opens in a new tab)MLA Style Center / Modern Language Association · MLA editorial guidance on internal prepositions in titles
  6. Inside — grammar and meaning (opens in a new tab)Cambridge Dictionary / English Grammar Today · Prepositional, adverbial, adjectival, and nominal roles of “inside”

Related guides

Writing & Style

APA Title Case

APA title case capitalizes the first word, the first word of a subtitle, major words, and words of four letters or more while keeping short minor words lowercase in ordinary mid-title positions.

Writing & Style

Chicago Title Case (18th Edition)

Chicago 18 uses title case for titles of works and changed a long-standing rule: prepositions of five letters or more are now capitalized. Shorter prepositions generally remain lowercase internally, while first and last words are capitalized and “to” remains lowercase as an infinitive marker in ordinary mid-title use.

Writing & Style

MLA Title Case

MLA 9 describes title style as capitalizing the first word, last word, and all principal words. MLA’s public Style Center also documents the traditional lowercase treatment of internal prepositions, but its detailed preposition article is edition-labeled for MLA 8, so this engine does not yet treat the full MLA 9 converter profile as complete.

Writing & Style

Prepositions in Title Case

Prepositions are one of the clearest places where title styles diverge. APA uses a four-letter major-word threshold, Chicago 18 capitalizes prepositions of five letters or more, and MLA editorial guidance generally lowercases internal prepositions regardless of length.

Writing & Style

Is “Outside” Capitalized in a Title?

Outside can function as a preposition, adverb, adjective, or noun. APA, Chicago 18, and MLA do not use one universal “small word” rule; capitalization depends on style and, where the word has multiple grammatical roles, on its function in the title.

Explore the topic

CapitalizationTitle CaseStyle Guides