Result
Yes. "Did" is the past tense of "do," usually a helping verb in a question ("What Did We Learn?"). Every style guide capitalizes verbs in a title, even three-letter ones.
"Did" by Style Guide
| Style guide | "Did" mid-title | Why |
|---|---|---|
| AP | Capitalize | Verbs are major words |
| APA | Capitalize | Verbs are major words |
| Chicago | Capitalize | Verbs are major words |
| MLA | Capitalize | Verbs are major words |
| AMA | Capitalize | Verbs are major words |
| Bluebook | Capitalize | Verbs are major words |
Examples in Chicago Style
- What Did We Learn This Year
- Why Did Our Traffic Drop
- How Did They Do It
- You Did It
"Do", "does", and "didn't" are capitalized for the same reason.
For the short list of words that do stay lowercase, see the full list of words that stay lowercase.
"Did" 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 "did" is lowercase unless it starts the title: "What did we learn this year." Pick one of the two styles for a whole set of headings rather than mixing them.
Quick Answers
Should "did" be capitalized in a title?
Yes. "Did" is a verb, and every style guide capitalizes verbs in title case.
Is "did" capitalized in APA?
Yes. APA capitalizes major words, including verbs, regardless of length.