When to Use a Colon in AP Style Writing

When it comes to grammar, the use of a period, question mark or exclamation point seems straightforward. They were the first grammatical marks you read and learned. Semicolons, colons and other punctuation seem daunting because they occur in formal writing and have specialized uses.

Mechanics of Using a Colon

Semicolons and colons are different regardless of having the same root word. Colons seem hard to use because there are more rules about their use. Placing a period at the end of a complete sentence is simple. You leave a space and capitalize the next word. A colon is a bit trickier because you must consider context.

Lists of Things

One of the most common ways of when to use a colon is with a list either within a sentence or as a vertical ordering of items. In the latter case, you should treat complete sentences as you normally would with the first word capitalized and appropriate punctuation at the end.



  • Paper
  • Pencil
  • Rulers


  • Who had a motive?
  • What happened?
  • Where was each of the suspects?

Independent Clauses

You can also use a colon to unite two independent clauses. An independent clause is a sentence that can stand on its own as a complete thought. The two clauses must be related with the second as an adjunct to the first.

You shouldn’t capitalize the first word of the second clause unless the more than one sentence follows it on the right.


  • He finally bought a Harley Davidson: it was his dream since college.
  • Her book was published: It took her five years to finish it. Random House bought it.

Introductions and Emphasis

Like em dashes and ellipses, you can also use a colon to introduce another sentence to emphasize something by using it in place of a word like namely. It functions as a list but adds emphasis since there is only one item following it.


  • My dad believed there was only one great brand of car: Cadillac.
  • There was one more thing on his bucket list: go to France.

Special Scenarios

There are also several special cases for when to use a colon. In formal business correspondence, you should use a colon in the salutation rather than a comma as in informal letters. Other examples include time figures and Bible verses.


  • Dear Mr. Smith:
  • 3:15
  • John 15:12

Introducing Quotations

A quotation often contains a complete sentence, so using a colon in the introduction makes sense since the two are most likely independent clauses. It adds clarification especially if the quote is more than six words.


  • Let’s remember Winston Churchill’s advice: ‘If you’re going through hell, keep going.”

How to Use a Colon

Like other special punctuation, you should use colons where appropriate. If you’re using them for emphasis, keep this adage in mind: less is more. It works best if it has the center stage. Don’t crowd the platform with actors screaming to be heard. Let the well-placed colon steal the show.

Vincent D'Eletto

Vincent D'Eletto

Hey, I'm Vin. Founder and CEO of WordAgents.com. I create content that ranks really well on search engines for our clients. I'm also deeply involved with the SEO community; maintaining a portfolio of successful, profitable affiliate websites. You can find me playing guitar, drinking scotch, and hanging out with my German Shorthaired Pointer when I'm not working!