Writing & StyleWord guide

Is “Through” Capitalized in a Title?

APA capitalizes “Through” internally because it has at least four letters. Chicago 18 also capitalizes it when used as a preposition because current Chicago capitalizes prepositions of five letters or more. MLA treatment still depends on grammatical function, so prepositional and principal-word uses should not be collapsed into one rule.

Reviewed2026-09-26Evidence6 sourcesSectionWriting & Style

Quick answer

APA: capitalize. Chicago 18: capitalize. MLA: normally lowercase when “through” is a preposition, but capitalize a principal-word use; first/last-word rules can override ordinary internal treatment.

Key details

APA 7Capitalize internally because it has seven letters.

Automation NoteBoundary rules override ordinary internal treatment. MLA role-sensitive uses remain review-only unless the phrase structure is established safely.

Chicago 18Capitalize internally; Chicago 18 capitalizes prepositions of five letters or more and principal words.

MLA 9Lowercase as a preposition; capitalize principal-word uses such as adverbs/adjectives.

TermThrough

Word Classpreposition / adverb / adjective

Style-by-style guidance

APA 7

Capitalize internally because it has seven letters.

Chicago 18

Capitalize internally; Chicago 18 capitalizes prepositions of five letters or more and principal words.

MLA 9

Lowercase as a preposition; capitalize principal-word uses such as adverbs/adjectives.

Important caveats

Automation boundary

APA and current Chicago are deterministic for this spelling in ordinary internal position, but MLA still requires grammatical-role awareness. Multiword-preposition recognition is treated as structure metadata, not as permission to guess.

Further guidance

Practical Application

Apply the title-case rule by style and grammatical role. APA capitalizes “Through” internally because it has seven letters; Chicago 18 capitalizes prepositions of five letters or more; MLA normally lowercases it when it functions as a preposition but capitalizes a principal-word use.

Quick rule

Reader Check

Which style governs the title, and in MLA is “through” functioning as a preposition or as another principal word? Boundary position can override the ordinary internal rule.

Worked Example

Example: an internal prepositional “through” is capitalized in APA and Chicago 18, while MLA normally lowercases that prepositional use; do not force one universal answer across all styles.

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.

Title case capitalization (opens in a new tab)American Psychological Association · APA title-case rules
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
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
How should I capitalize the title of a handout? (opens in a new tab)MLA Style Center / Modern Language Association · MLA title-style capitalization
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
THROUGH — English meaning and grammar roles (opens in a new tab)Cambridge Dictionary · Part-of-speech and usage context for “through”

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Is “About” Capitalized in a Title?

APA capitalizes “About” internally because it has at least four letters. Chicago 18 also capitalizes it when used as a preposition because current Chicago capitalizes prepositions of five letters or more. MLA treatment still depends on grammatical function, so prepositional and principal-word uses should not be collapsed into one rule.

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Is “Across” Capitalized in a Title?

APA capitalizes “Across” internally because it has at least four letters. Chicago 18 also capitalizes it when used as a preposition because current Chicago capitalizes prepositions of five letters or more. MLA treatment still depends on grammatical function, so prepositional and principal-word uses should not be collapsed into one rule.

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