"Through" is a 7-letter preposition. Because it clears every length cutoff in use, the only guides that keep it lowercase mid-title are the ones that lowercase prepositions regardless of length: Chicago and MLA.
This guide breaks down the rule for "through" across eight style guides, with real examples and the mistakes that produce inconsistent titles.
Quick Answer
The rule for "through" depends on the style guide. In Chicago and MLA, keep "through" lowercase in a title unless it is the first or last word, because both lowercase prepositions of any length. In APA, AP, AMA, and the New York Times, capitalize "Through" mid-title because all four capitalize words of four or more letters. At 7 letters, "through" also clears the five-letter cutoff used by Wikipedia and Bluebook, so those guides capitalize it too.
You can apply this automatically by pasting your title into the title case converter at the top of the page and choosing your style.
Quick Reference: "Through" by Style Guide
| Style Guide | Capitalize "Through"? | Rule |
|---|---|---|
| Chicago (CMOS) | No | Lowercase prepositions of any length |
| MLA | No | Lowercase prepositions regardless of length |
| APA (7th edition) | Yes | Capitalize words of 4 or more letters |
| AP (Associated Press) | Yes | Capitalize prepositions of 4 or more letters |
| AMA | Yes | Capitalize words of 4 or more letters |
| New York Times | Yes | Capitalize prepositions of 4 or more letters |
| Wikipedia | Yes | Capitalize prepositions of 5 or more letters |
| Bluebook | Yes | Capitalize prepositions of 5 or more letters |
Why Style Guides Disagree on "Through"
Title-case guides fall into two camps. Length-based guides capitalize any preposition over a set letter count: APA, AP, AMA, and the New York Times use a four-letter cutoff, while Wikipedia and Bluebook use five. "Through" clears both, so all six capitalize it. Category-based guides like Chicago and MLA lowercase every preposition regardless of length, treating prepositions as connective tissue that should not compete with nouns and verbs for emphasis. For the full picture, see title case prepositions: the 1 to 4 letter rule.
Chicago and MLA
Both Chicago and MLA keep "through" lowercase in the middle of a title. The exception in both guides is position: capitalize "Through" when it is the first word, the last word, or directly follows a colon that introduces a subtitle.
APA, AP, AMA, and NYT
All four length-based guides capitalize "Through" because it passes the four-letter threshold. For the full APA breakdown, see the APA title case rules, and for AP see the AP title capitalization rules.
Wikipedia and Bluebook
Wikipedia and Bluebook use a five-letter cutoff for prepositions. At 7 letters, "through" sits above that line, so both capitalize it in any title position.
When to Capitalize "Through" in Any Style
Regardless of guide, capitalize "Through" when it is the first word of the title, the last word, or the first word of a subtitle after a colon. Outside those positions, the length rule of your chosen style decides, and for "through" that means capitalized everywhere except Chicago and MLA.
Real Titles That Use "Through"
- Through the Looking-Glass by Lewis Carroll. "Through" capitalized as the first word.
- A Walk Through History. "Through" capitalized mid-title in APA, AP, AMA, and NYT.
- Halfway Through the Story. Chicago and MLA keep "through" lowercase.
- Notes Through the Years. Length-based guides capitalize "Through".
Common Mistakes
The most common error is lowercasing "through" everywhere because it feels like a small connecting word. In APA, AP, AMA, and NYT it should be capitalized mid-title because of its length. The opposite mistake is capitalizing "Through" in Chicago or MLA, where every preposition stays lowercase regardless of length. The fix for both is to pick one style guide and apply it across every title in the document rather than switching between them.
