It Depends
The Short Answer
Colons are one of the few punctuation marks where capitalization rules genuinely change depending on which style guide you follow. This isn't a case where one answer is "more correct" – AP, Chicago, and APA each have a defensible rule, and they disagree with each other.
The confusion makes sense. A colon sits between two related parts of a sentence, and reasonable people disagree on whether what follows it deserves the same treatment as a new sentence. If you're writing for a specific publication or institution, check their style guide. If you're writing for yourself, pick a rule and stick with it.
Here's how the main style guides handle it.
Quick Rules
Capitalize when
- AP style: a complete sentence follows – There was one problem: The server crashed overnight.
- APA style: a complete sentence follows – The results were clear: Participants preferred the shorter version.
- Chicago style: two or more complete sentences follow – She had two goals: First, she wanted to finish the report. Second, she needed to send the invoice.
- Any style: a proper noun follows the colon – The winner is: Sarah.
Keep lowercase when
- A fragment or list follows: She packed three things: a book, a pen, and a notebook.
- A single word or phrase follows: There's only one word for it: chaos.
- Chicago style with one sentence after the colon: She had one goal: she wanted to finish the report.
- MLA style (most conservative): lowercase unless a proper noun or original capitalized quotation follows.
Tip: When in doubt, lowercase after a colon is the safer choice in everyday writing. It's never wrong when the colon introduces a fragment – and most things after colons are fragments.
Style Guide Breakdown
AP Style has the simplest rule: capitalize the first word after a colon if what follows is a complete sentence. Doesn't matter if it's one sentence or five. Complete sentence = capital letter. Fragment = lowercase. Most journalism follows this.
Chicago Style is more conservative. It capitalizes after a colon only when two or more complete sentences follow. If just one sentence follows, lowercase. This is the standard for book publishing and academic writing outside the sciences.
APA Style aligns with AP on this one – capitalize if a complete sentence follows the colon. APA adds a specific rule for colons in titles: always capitalize the first word after a colon in a title or heading, regardless of what follows. This matters for academic papers and research titles.
MLA Style keeps it lowercase after a colon unless the first word is a proper noun or begins a quotation that was capitalized in the original. MLA is the most conservative approach.
Examples
✓ Do
- She had one request: don't be late. (Chicago – one sentence, lowercase)
- She had one request: Don't be late. (AP/APA – complete sentence, capitalize)
- The recipe calls for three ingredients: flour, sugar, and butter.
- The title read: "Capitalizing After Colons: A Complete Guide"
✗ Do not
He bought: Apples, oranges, and bananas.
A fragment follows the colon – always lowercase: He bought: apples, oranges, and bananas.
The store sold two things: Bread and milk.
"Bread and milk" is a fragment, not a sentence. Lowercase in all major style guides.
He Said: "we should go now."
If the quoted material was capitalized originally, keep it. If not, lowercase. And never capitalize "said."
Edge Cases Worth Knowing
These scenarios trip up even experienced writers because each one has a different rule from what you'd expect.
- Colons before lists. Always lowercase when the colon introduces a vertical or inline list – even if each list item is a complete sentence. The instructions are simple: wash your hands, put on gloves, open the package. All major style guides agree here.
- Subtitles and headings. Capitalize the first word after the colon in titles and subtitles regardless of style guide: Harry Potter and the Prisoner of Azkaban: A Critical Analysis. APA explicitly requires this; AP, Chicago, and MLA all follow the same convention in title case.
- Multiple colons in one sentence. Don't do it. Restructure instead. One colon per sentence is the universal rule.
- Colons introducing quotations. If the quotation is a complete sentence, capitalize regardless of style guide – the capital letter belongs to the quoted material: She said: "The meeting starts at noon." If you're weaving a partial quote into your own sentence, lowercase: She described the mood as: "tense but hopeful."
- Colons in dialogue and scripts. In screenplays and play scripts, the character name followed by a colon always leads to a capitalized line: JOHN: We need to leave. This is a formatting convention, not a grammar rule.
Frequently Asked Questions
Writing titles with colons? Our free Title Case Converter handles post-colon capitalization across AP, APA, Chicago, and MLA styles automatically.
Open the converter with a prefilled example and adapt it to your headline.
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About Oleh Kovalenko
Oleh Kovalenko develops practical capitalization guidance for editorial and SEO workflows, with a focus on consistent rule application.
