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difference between ap and chicago style

Writing Style Guides: The Difference Between AP and Chicago

English is all English, isn’t it? Does it really matter how you place the apostrophe or comma? Yes, it does. There are a ton of style guides writers and editors use to govern what goes where and how it appears. There’s MLA, AP, APA, AMA–seriously, the list goes on.

For our purposes, we’ll focus on the most common two: Associated Press Style (AP)–used mainly for PR and journalistic purposes–and the Chicago Manual of Style (CMOS) used for books, periodicals, and journals.

Among grammarians, editors, and writers the most debatable is “where does the comma go?” So, we’ll start there.

How to Use Commas

The serial comma (properly known as the “Oxford comma”) has AP and Chicago users in a debate on its usage. So thank goodness for the following rules.

The AP style omits the last comma in a series:

The sunset filled the sky with hues of purple, blue and orange yesterday.

The Chicago includes it:

The sunset filled the sky with hues of purple, blue, and orange yesterday.

When to Write Out Numbers

A ton of the authors I work with confuse this rule. Remember, book writing always follows CMOS.

AP Style spells out numbers nine and below. 

At age nine, I had birds as pets.

CMOS Style spells out all numbers from zero to ninety-nine. 

Grandma always said she had thirty-one recipes for chicken: one for each day of the month.

Using the Em Dash

In AP style, en dashes “-” are never used. Therefore, when “dashes” is said in AP, you can assume someone is referring to the em dash and only that.

Generally, in AP or Chicago style, em dashes are used in the following instances:

  • Datelines

PARIS —  Notre Dame went into flames last night, reported one official who was on the premises.

  • Attributions

“The past is always tense, the future perfect.” — Zadie Smith

  • To make a phrase stand out, also referred to as abrupt change

The man stole $152,000 worth of jewelry — and left it on his front porch — police discovered after finding him at his New England residence.

  • In lists

She was quite the entertainer — a dancer, singer, actress, and musician — who captivated the audience’s attention.

But how do you use em dashes? It depends . . .

AP style places a space  before and after em dashes:

I love shopping — except during the busy holiday season — for new shoes.

CMOS doesn’t have any spaces before and after em dashes:

I love shopping—except during the busy holiday season—for new shoes.

How to Use Ellipses in a Sentence

Much like em dashes, ellipses have their own spacing rules.

AP places a space before and after ellipses:

I miss those days … sweet and bright.

CMOS places a space between each period and before and after its appearance:

I miss those days . . . sweet and bright.

Are Titles in Quotes or Italics?

AP likes quotes. Even for major works.

“The Great Gatsby” is one of the greatest works of literature.


 Jane Austin is best known for Pride and Prejudice and Emma.

Be sure that for whichever guide you use to purchase a copy of its “rule book.” You’ll be a better writer or editor because of it.

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