AP vs. Chicago style: What’s the difference between these two guides?

AP vs. Chicago style: What’s the difference between these two guides?

by Andrea Byaruhanga

Updated May 11, 2022

You may have heard of the Chicago Manual of Style and the AP Stylebook, but what do you know about them? 

Both of these books provide writers and editors with guidelines to ensure that they’re producing and publishing error-free content. But these guides, for the most part, are used for vastly different purposes—and they don’t typically agree on what “error-free content” is.  

Below, we detail some of the main differences between AP vs. Chicago style, highlight a couple of similarities and talk about who should use which guide.

Learn languages at your pace


What’s the difference between AP style and Chicago?

Though they’re both style guides, the Chicago Manual of Style (CMOS) and the Associated Press (AP) Stylebook are very different. 

The larger of the two guides, the Chicago Manual of Style caters to a wide range of writing styles. It provides tons of technical detail about editing a variety of content and using the correct layout. The CMOS provides separate, in-depth sections on formatting charts and tables, quotations, citations, numbers, etc. and includes many examples.

Alternatively, the AP Stylebook focuses on rules for correctly constructing a news article and has a heavy emphasis on grammar—in fact, more than half the book deals with grammatical issues. 

On top of that, the book also includes a combination dictionary/thesaurus/encyclopedia to clarify commonly mistaken words, places and ideas. Things like punctuation, capitalization and abbreviations are covered as well.

Here are a few key usage differences between the CMOS and AP Stylebook.

Accents

In Chicago style, you should use accents in foreign words.

Example: Let’s meet up at the café.

AP states that you shouldn’t use accents in foreign words.

Example: Let’s meet up at the cafe.

Book titles

Chicago style book titles should be in italics.

Example: I really enjoyed reading The Long Walk to Freedom. 

AP style book titles should be in quotation marks.

Example: I really enjoyed reading “The Long Walk to Freedom.”

Ellipses

Chicago style says that ellipses should contain spaces.

Example: “Nobody knows . . . ” she began.

There’s no space between ellipses in AP style.

Example: “Nobody knows … ” she began.

Em dashes

Chicago favors the use of an em dash with no space on either side. 

Example: The boy was tired—not to mention hungry and dehydrated. 

AP, on the other hand, states that there should be a space on either side of the em dash. This is because newspapers usually follow AP style and the spaces help the layout of the narrow columns of text. 

Example: The boy was tired — not to mention hungry and dehydrated. 

Numbers

According to the CMOS, you should spell out numbers 0 to 99. For numbers 100 and up, you can use numerals.

Example: There were thirty-three guests at the dinner party last night.

AP style says you only need to spell out numbers under 10 before switching to numerals.

Example: There were 33 guests at the dinner party last night. 

Oxford commas

You almost always use an Oxford (aka serial) comma in Chicago style. 

Example: I love pizza, pasta, and all seafood.

An Oxford comma is almost never used in AP style unless it helps avoid confusion.

Example: I love pizza, pasta and all seafood.

Possessive apostrophes with singular proper nouns ending in “s”

In Chicago style, you should add an apostrophe and an “s” at the end of a singular proper noun that ends in an “s.”

Example: Isn’t that Davis’s dog running down the street? 

In AP style, you would only add an apostrophe to a singular proper noun ending in “s.”

Example: Isn’t that Davis’ dog running down the street? 

Sources

Chicago style has two systems for source citations: 

  • Author-date
  • Notes and bibliography

When using AP style, you’ll typically mention sources within the text rather than in a bibliography.

Title case capitalization

In Chicago style, you should never capitalize a preposition in the title case unless it’s at the beginning of the title.

Example: Have you ever read “A Long Way from Home”?

In AP style, you capitalize any word four letters or longer in a title.

Example: Have you ever read “A Long Way From Home”?

Learn languages at your pace

AP style and Chicago: How are they similar?

Chicago and AP styles are definitely more different than similar. However, there are a couple of elements on which they agree.

Percentage symbol

In the past, the AP style didn’t allow for the use of the percentage symbol (%). The style guide has now joined Chicago in stating that the percentage symbol is okay when paired with a numeral. 

Example: I think about 90% of the population is addicted to their phones. 

Possessive apostrophe for common nouns ending in “s”

Plural 

Chicago and AP style agree that you should only use an apostrophe to show possession when dealing with a plural common noun. 

Example: The kids’ ice cream cones were melting quickly.

Singular

Both styles state that you should use an apostrophe and an “s” with a singular common noun that ends with “s.” 

Example: I love Las Vegas’s bright lights. 

One exception in AP is that if the word following the common noun begins with an “s,” as “sights” does in the example below, then you’d only add an apostrophe to the common noun, not an apostrophe and an “s.” 

Example: I love Las Vegas’ sights (not Las Vegas’s sights).

AP vs. Chicago style: When should each style be used?

The AP Stylebook is geared toward writers of news stories, articles and blog posts. It’s also for those who deal with news releases and public relations. It’s ideal as a quick reference guide when you need to quickly and correctly disseminate information. 

The Chicago Manual of Style, on the other hand, better serves those who write long-form content, academic papers and fiction since it’s much more concerned with the technical details like quotations and punctuation. 


Choose the right style guide for you

We hope we’ve shed some light on the differences between AP and Chicago styles. Whether you’re writing a blog post, an academic paper or a romance novel, using the right style will give you the direction you need to produce clear, correct, high-quality content. 

Learn languages at your pace


Andrea is a Canadian freelance writer and editor specializing in English, e-learning, EdTech, and SaaS. She has a background as an ESL teacher in beautiful Vancouver, British Columbia. In her free time, Andrea loves hanging out with her husband and son, creating recipes in the kitchen, and reading fiction. She also loves camping and jumping into lakes whenever possible. Learn more about Andrea on LinkedIn or check out her website.

Related articles