Should You Capitalize the First Word of a Sentence after a Colon?

My previous post, “How to Use Colons,” explains that colons can introduce lists and quotations, conclude salutations, and link titles with subtitles. Colons can also connect tightly coupled sentences, such as those with a cause-and-effect or problem–solution relationship. Today’s post tackles the question of whether you should capitalize the first word of a sentence after a colon.

This topic deserves its own post because there is no “absolute” answer. Instead, the decision to use a capital or lowercase letter will depend on your style guide. And as usual, the style guides don’t always agree.

Here is a summary of the recommendations provided by four of our primary style guides: The Chicago Manual of Style (Chicago style), MLA style from the Modern Language Association, ¹ The Associated Press Stylebook (AP style), and the Publication Manual of the American Psychological Association (APA style).

Capitalization after Colons — Chicago Style and MLA Style

The Chicago Manual of Style (Chicago style) and MLA style from the Modern Language Association recommend lowercasing the first word of a sentence after a colon unless the colon precedes multiple closely related sentences, in which case the first word should be capitalized.²

The train is scheduled to arrive forty-five minutes late: a herd of cattle is crossing the tracks.

The train is scheduled to arrive forty-five minutes late: A herd of cattle is crossing the tracks. The cows are taking their time.

Note that Chicago style’s student version, commonly called Turabian, also capitalizes the first word after a colon if the colon comes before more than one related sentence.³

Capitalization after Colons — AP Style and APA Style

The Associated Press Stylebook (AP style) and the Publication Manual of the American Psychological Association (APA style) suggest capitalizing the first word of any complete sentence following a colon.⁴

The writer debated the future of her long-unfinished work: Should she finish the novel or start a new one?

What about Colons before Quotations?

In some cases, colons can introduce run-in quotations that are complete sentences. They can also introduce block quotations beginning with a complete sentence. In both situations, the first word of the quotation is capitalized.

Bartholomew answered: “Yes, of course I want more pretzels.”

See the following posts for more information about using colons with quotations:

How to Introduce Run-in Quotations

Block Quotations, Part 1: How to Introduce Block Quotations

If you haven’t chosen a style guide and are wondering which one to follow, I always recommend Chicago style for general writing, business writing, and writing geared to traditional publishing. Check out “Which Style Guide Is Best for You?” for more information on the guides mentioned here and “Alternative Style Guides” for several additional options.

References

1. The MLA Handbook does not address capitalization after colons, so all the MLA style information presented here comes from the MLA Style Center website, which is the handbook’s official online extension.
2. The Chicago Manual of Style, 17th ed. (Chicago: University of Chicago Press, 2017), 6.63; “Colons: How to Use Them,” Behind the Style, The MLA Style Center, accessed October 27, 2019.
3. Kate L. Turabian, A Manual for Writers of Research Papers, Theses, and Dissertations, 9th ed. (Chicago: University of Chicago Press, 2018), 21.4.
4. The Associated Press Stylebook 2019 (New York: The Associated Press, 2019), 323; Publication Manual of the American Psychological Association, 7th ed. (Washington, DC: American Psychological Association, 2020), 6.5, 6.13.