The “capitalize after colon” question is a bit divisive.
So, it pays to know what the different style manuals have to say about it.
What you learned with the MLA handbook in high school doesn’t necessarily apply to that article for a psychology blog.
Also, the rules are a bit different between American and British English.
We’ve listed all the rules to make it easier for you to know when to capitalize after a colon, depending on where and what you’re writing.
Do You Capitalize After a Colon?
We’ll start with the main rules to remember and then cover the differences in colon usage between different countries and style manuals.
Capitalization after Colon Rules
Rule #1: Horizontal Lists
When you use a colon to introduce a horizontal (i.e., in-line) list of words or phrases, do not capitalize the first word after the colon unless it’s a proper noun.
- Incorrect: “He wants a farm that specializes in three animals: Pigs, goats, and chickens.”
- Correct: “He wants a farm that specializes in three animals: pigs, goats, and chickens.”
- Correct: “He invited three of my coworkers to the picnic: Alex, Janis, and Rory.”
Rule #2: Vertical Lists
When a colon introduces a vertical list (bulleted or numbered), capitalize each list item.
“He created a simple morning routine with the following tasks:
- “Drink a glass of water.”
- “Brush teeth.”
- “Exercise for 5 minutes.”
- “Write morning journal entry.”
- “Eat breakfast.”
Rule #3: Within a Sentence
When a colon introduces a word, phrase, or incomplete sentence, do not capitalize the first word after the colon unless it’s a proper noun.
- Incorrect: “She made me a quilt with my favorite colors: Purple and light green.”
- Correct: “She made me a quilt with my favorite colors: purple and light green.”
- Correct: “She invited my best friends to the party: Oliver, Felicity, John, and Sarah.”
Rule #4: Complete Sentences after the Colon
When a colon introduces a complete sentence, you may capitalize the first word after the colon depending on the style guide you use.
- “He took the job with one expectation: he would earn enough to move into the apartment he wanted.” — Correct for AP and APA styles; Incorrect for Chicago Manual of Style and MLA.
You’ll see more on this in the section on “Differences in Capital after Colon Rules.”
Rule #5: Questions
Questions are (generally) complete sentences with a distinction that sets them apart: they immediately get your mind working on an answer.
Because of this, they demand more thoughtful attention than the average sentence.
- Incorrect: “It all boiled down to one question: which of the two brothers was lying?”
- Correct: “It all boiled down to one question: Which of the two brothers was lying?”
Rule #6: Quotes, Rules, and Principles
Capitalize the first word of any quote, rule, or principle that follows a colon in a sentence, just as you would with a question.
All of these tend to be written as complete sentences (i.e., independent clauses). And even the style guides that don’t generally recommend capitalizing a single independent clause after a colon set these particular types of clauses apart as special cases.
- “I have only one rule for living in this house: Never invite a guest in without consulting me first.”
- “I asked him for a quote for my poster, and he gave me one: ‘
Rule #7: Subtitles
Capitalize a subtitle after the colon that separates it from the title.
It’s not just the first word that gets capitalized; subtitles are capitalized the same way titles are — in title case.
- Incorrect: “Outliers: the story of success”
- Incorrect: “Outliers: the Story of Success”
- Incorrect: “Outliers: The story of success”
- Correct: “Outliers: The Story of Success”
Important Differences in Capital after Colon Rules
#1 — U.S. vs. UK
British English (UK) capitalizes the first letter after a colon only if it’s a proper noun or an acronym.
- “The experience led him to one conclusion: Sam had lied to him.”
- “Yesterday, she told me about her dream job: CFO for a global corporation.”
In the U.S., American English sometimes capitalizes the first word after a colon if it starts a complete sentence, though it depends on the style manual being used.
#2 — Different Style Manuals
Depending on what you’re writing, one or more of the following style manuals may be more familiar to you. Here’s a short list based on the most common uses for each:
- AP Style — newspapers, magazines, and public relations offices
- APA Publication Manual — academic writings, scholarly journal articles, and books
- Chicago Manual of Style — book publishing (fiction and nonfiction) and some social science publications
- MLA Handbook (9th Ed) — academic/scholarly writing, especially in the humanities
The style manual you use will have plenty to do with whether you capitalize an independent clause that follows a colon.
The AP Stylebook and the APA Publication Manual both recommend capitalizing the first word of an independent clause that follows a colon.
- Example: “He told her only one thing before he left: He had a promise to keep.”
The Chicago Manual of Style and the MLA Handbook, on the other hand, only capitalize after a colon in one of the following cases:
- Case #1: Two or more independent clauses follow and explain the clause before the colon.
- Case #2: The sentence after the colon is a question, quote, rule, or principle.
- Case #3: The first word of the independent clause after the colon is a proper noun.
Examples with two independent clauses after a colon:
- Incorrect: “He gave us only two rules: first, clean up your own messes. Second, always lock the door when leaving the apartment.”
- Correct: “He gave us only two rules: First, clean up your own messes. Second, always lock the door when leaving the apartment.”
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Some Final Notes on Colon Usage
Rule #1: Do not use a colon between two clauses unless the second one explains, answers, or amplifies the first one.
- Incorrect: “He knew why she hadn’t come: he planned to discuss it with her later.”
- Correct: “He knew why she hadn’t come; he planned to discuss it with her later.”
- Or “He knew why she hadn’t come, and he planned to discuss it with her later.”
- Or “He knew why she hadn’t come. He planned to discuss it with her later.”
- Correct: “He knew why she hadn’t come: she’d discovered his secret.”
Rule #2: When using a colon in a sentence, it goes after an independent clause, not a verb.
- Incorrect: “His favorite dinner choices are: spaghetti, pizza, or Chinese take-out.”
- Correct: “His favorite dinner choices are spaghetti, pizza, or Chinese take-out.”
Now that you’ve looked through the rules on capitalization after colons—and the main differences mentioned here—what stood out for you? What did you find most surprising or useful?