AP vs Chicago Style: Why You Should Care

Ah, style guides—where the battle lines are drawn, the stakes are high, and the Oxford comma is revered or reviled.

Whether you’re a freelance writer, novelist, or aspiring journalist, understanding the key differences between Associated Press (AP) style and The Chicago Manual of Style ("Chicago style" or "CMOS") will help you write better, more consistent content.

AP style is dominant in journalism but also common in blogging, online articles, press releases, social media marketing, and corporate communications. Most of the content on the web is written in AP style.

Chicago style is dominant in books, academic research, white papers, magazines, fiction, some large organizations, and content written by people who just prefer the Chicago vibe.

As a fiction publisher, Lake Eerie Books uses Chicago style and encourages our authors to use it as a grammar and stylistic reference.

Why Are AP Style and Chicago Style Different?

AP's Stylebook was developed for newspaper journalists in the mid-20th century (but has been frequently updated ever since). Because of its roots in print journalism, AP style tends to avoid special characters (such as italics), which didn't transfer well over wire or print consistently on different presses. AP style also emphasizes efficient use of space, such as "59" instead of "fifty-nine", due to the narrow columns of traditional newspaper layouts.

Chicago style, with its roots in books and academic manuscripts, allows for italics and other special characters. It sacrifices some efficiency for a classic, polished look and isn't as concerned with saving space: "seventy-eight" versus "78".

To the modern eye, Chicago style looks a bit more traditional and elegant, while AP style looks contemporary and concise. For instance:

AP style: Among The Who's 12 studio albums, "Tommy" ranks first.

Chicago style: Among The Who's twelve studio albums, Tommy ranks first.

In this article, we’ll look at eight key differences between AP and Chicago and provide examples along the way. There are hundreds of other differences, but these are common ones that every writer should know.

The Oxford Comma

It's safe to say no one in the writing business is neutral about the Oxford comma. Also known as the serial comma, it's the comma used immediately before the coordinating conjunction (usually “and” or “or”) in a list of three or more items. AP and Chicago hold opposing views on this contentious punctuation mark.

AP style: She bought apples, oranges and pears.

Chicago style: She bought apples, oranges, and pears.

Many writers use the Oxford comma even while generally preferring AP style. The Oxford comma can appear slightly academic but ensures clarity and prevents ambiguity.

If you're thinking the Oxford comma seems stodgy and unnecessary, consider the following:

I love my parents, Lady Gaga and Superman. (credit: wjrock.com)

Possessive Apostrophes: We KNOW Which One You're Going To Hate

In AP style, if you have a proper noun ending in “s” and want to put it in possessive case, just add an apostrophe. In Chicago Style, you add an apostrophe and an “s”.

AP style: Carlos' favorite hobby was bike racing.

Chicago style: Carlos's favorite hobby was bike racing.

Ellipses

These are the three dots that indicate a ... pause. Some writers love them; others hate them. AP treats ellipses as three-letter words with a space on either side, just like any other word. Chicago, on the other hand, prefers spaces between each dot but no spaces before and after the ellipses.

AP style: Sandra was ... well, speechless.

Chicago style: Sandra was. . .well, speechless.

Abbreviating Months

AP style requires abbreviations for most months when used with a specific date, while Chicago style recommends spelling out months in their entirety.

AP style: Abbreviate months (except May, June, and July). Example: The event will take place on Oct. 12, 2023.

Chicago style: The event will take place on October 12, 2023.

On a related note, AP style omits the comma between the month and year when no date is given: The meeting is scheduled for May 2023. Chicago style employs the comma: The meeting is scheduled for May, 2023.

Titles of Works: Italics vs. Quotation Marks

In AP style, quotation marks are used for the titles of all works, while CMOS distinguishes between larger and smaller works. Larger works, like books and movies, are italicized, while smaller works, such as articles or songs, are enclosed in quotation marks.

AP style: She loved the song “Bohemian Rhapsody” by Queen.

Chicago style: She loved the song “Bohemian Rhapsody” from the album A Night at the Opera.

Another example. AP style: "The Color Purple." Chicago style: The Color Purple.

Numbers

AP and Chicago have different guidelines for numbers. In AP style, numbers one through nine are spelled out, while numerals are used for 10 and above. In Chicago style, numbers are spelled out all the way to a hundred.

AP style: Maddie has six cats and 12 dogs.

Chicago style: Maddie has six cats and twelve dogs.

Honestly, with eighteen cats and dogs, Maddie has bigger issues than whether to spell out "12", but that is beyond the scope of this article.

Capitalization and Numbers in Headlines

In AP headlines, only the first word and proper nouns are capitalized, similar to how you would write any other sentence. This is called Sentence Case. In Chicago style, most words in a headline are capitalized, with the exception of articles, prepositions, and conjunctions with fewer than five letters. This is called Title Case.

AP style: Senate approves new healthcare bill

Chicago style: Senate Approves New Healthcare Bill

The headlines in this blog post are written in Chicago style.

AP style uses numerals in headlines, while Chicago spells out the numbers.

AP style: 3 cats discovered in storm-ravaged town

Chicago style: Three Cats Discovered in Storm-Ravaged Town

Some writing sites such as Medium prefer title case in the main headline and sentence case in subheadings. It's best to check on the stylistic standards for any forum on which you intend to submit your work.

They use different dictionaries!

Can't everyone at least agree to use the same dictionary? Nope.

AP style and the New York Times use Webster's New World College Dictionary, 5th edition. Chicago and MLA (another popular style guide) use Merriam-Webster's Collegiate Dictionary, 11th edition. Those are links in case you decide to buy one.

You won't be too surprised to learn that most entries are similar: there are only so many different ways to define "lightbulb." But what about newer words like "selfie"? In fact, there are key differences between the dictionaries, especially around newer, tech-related words, so you really need to use the dictionary that matches your chosen style guide.

Merriam-Webster has a website with full, free access to its ever-growing and frequently-updated online dictionary. It's a tremendous resource that should be glued to any writer's or editor's browser bar. But beware: the insanely good website is not exactly the same as their Collegiate Dictionary, 11th edition. The Collegiate Dictionary is what you need for full compliance with Chicago style.

Conclusion

AP style and Chicago style are designed to bring consistency and clarity to your written words. They have differences, but either can be used unless you work for an organization with an official style guide. If you have the freedom to choose, the key is to choose the style that best suits your project and stick to it. Consistency is king.