Title capitalization guide
Is "This" Capitalized in a Title?

Yes — "this" is always capitalized in title case because it is a pronoun or determiner.

demonstrative pronoun or determiner
Capitalized in 7 styles
Lowercase in 3 styles
Title Case
YES
Capitalized — demonstrative pronouns are content words
AP Style
YES
Capitalized — pronouns and determiners are capitalized
NYT Style
YES
Capitalized — pronouns and determiners are capitalized
Chicago Style
YES
Capitalized — principal word in Chicago Style
MLA Style
YES
Capitalized — demonstratives are always capitalized
APA Style
no
Sentence case — only first word and proper nouns
AMA Style
YES
Capitalized — pronouns and determiners are capitalized
BB Style
YES
Every word capitalized — no exceptions
Wikipedia Style
no
Sentence case — only first word and proper nouns
Sentence Case
no
Only the first word of a title is capitalized

The full answer

"This" is a demonstrative pronoun or determiner and is always capitalized in title case. AP Style, Chicago Style, MLA Style, NYT Style, and AMA Style all treat "this" as a content word requiring capitalization.

The word is four letters long, which occasionally causes writers to wonder whether it falls under the short-word rule. It does not. The short-word lowercase rules apply to articles, conjunctions, and prepositions, not to pronouns or determiners.

APA Style, Wikipedia Style, and Sentence Case lowercase "this" in the middle of a title because those styles use sentence case rather than title case.

"This" is a very common title word, appearing in countless books, articles, songs, and films. Every title case style guide consistently capitalizes it, making it one of the easier words to get right.

"This" functions as a demonstrative pronoun when it stands alone to refer to something — "This Is Important" — and as a demonstrative determiner when it modifies a noun — "This Time Around." In both cases, it is capitalized in title case.