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

No in most style guides — "for" is lowercase in AP Style, Chicago Style, and MLA Style.

coordinating conjunction or preposition
Capitalized in 2 styles
Lowercase in 8 styles
Title Case
no
Lowercase as both a coordinating conjunction and a short preposition
AP Style
no
Lowercase as a conjunction and as a preposition
NYT Style
YES
Capitalized — NYT Style capitalizes prepositions
Chicago Style
no
Lowercase — three letters and a coordinating conjunction
MLA Style
no
Lowercase as a coordinating conjunction or preposition
APA Style
no
Sentence case — only first word and proper nouns
AMA Style
no
Lowercase as a conjunction and as a preposition
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

"For" is unique because it belongs to two categories that both result in lowercase: it is both a coordinating conjunction (FANBOYS) and a preposition. AP Style, Chicago Style, MLA Style, and AMA Style all lowercase it in the middle of a title.

"For" also functions as a preposition meaning "on behalf of" or "in exchange for." Whether it is functioning as a conjunction or a preposition, every major style guide that uses title case lowercases it in the middle of a title.

The double classification makes "for" one of the least ambiguous words in title case. There is no grammatical role it can play that would make it a content word requiring capitalization under AP Style or Chicago Style.

"For" as the first or last word of a title is always capitalized. Titles like "For Whom the Bell Tolls" capitalize "For" because it is the opening word, not because of its part of speech.

"For" is one of the seven coordinating conjunctions in the FANBOYS group, alongside "and," "nor," "but," "or," "yet," and "so." All seven are lowercased in title case by AP Style, Chicago Style, MLA Style, and AMA Style.