Result
It depends on the style guide. "Behind" is a six-letter preposition. AP, APA, AMA, and Bluebook capitalize prepositions that long, so they write "Behind." Chicago and MLA lowercase prepositions at any length, so "behind" stays lowercase there unless it is the first or last word, or works as an adverb.
"Behind" by Style Guide
| Style guide | "Behind" mid-title | Why |
|---|---|---|
| AP | Capitalize | Prepositions of four or more letters are capitalized |
| APA | Capitalize | Words of four or more letters are capitalized |
| Chicago | Lowercase | Prepositions are lowercase at any length |
| MLA | Lowercase | Prepositions are lowercase at any length |
| AMA | Capitalize | Prepositions longer than three letters are capitalized |
| Bluebook | Capitalize | Prepositions longer than four letters are capitalized ("behind" has six) |
The Same Headline in Four Styles
| Style | "the story behind the headline" |
|---|---|
| AP | The Story Behind the Headline |
| APA | The Story Behind the Headline |
| Chicago | The Story behind the Headline |
| MLA | The Story behind the Headline |
| Style | "left behind" |
|---|---|
| AP | Left Behind |
| APA | Left Behind |
| Chicago | Left Behind |
| MLA | Left Behind |
At the end of a title ("Left Behind"), "behind" is capitalized in AP, Chicago, and MLA, and it is an adverb there anyway.
For every cutoff, see title case prepositions.
"Behind" in Sentence Case
APA reference lists, many news sites, and most UI text use sentence case instead of title case. There, only the first word and proper nouns get capitals, so "behind" is lowercase unless it starts the title: "The story behind the headline." Pick one of the two styles for a whole set of headings rather than mixing them.
Quick Answers
Should "behind" be capitalized in a title?
In AP, APA, AMA, and Bluebook, yes. In Chicago and MLA, no, unless it is the first or last word.
Is "behind" capitalized in APA?
Yes. APA capitalizes words of four letters or more.