Explainer: How to Use Oxford Commas, per AP Style

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Previous posts looked at the Barcelona Principles, the Metaversesocial conversation platformsoff the record and sonic branding. Today we review the Oxford comma.

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Despite the widely held belief that the Associated Press Stylebook bans the use of the Oxford—or serial—comma, there are certain sentences that require that final comma in a list for clarity.

However, who knew a tiny squiggle of a punctuation mark could be so controversial?

One of the most commonly misunderstood, unnecessarily complicated and hotly contested rules in the AP Stylebook is found in the comma (,) entry. A comma, of course, is a punctuation mark used to indicate a pause in a sentence. But commas can also be used to separate three or more items in a list.

Duh. So, what’s the controversy? For decades, a debate has raged among word nerds, journalists and other grammarians surrounding whether one comma in particular—the Oxford comma—is necessary. Unlike many other style guides, the AP Stylebook, widely considered the “bible” for journalists and many comms people, does not use the Oxford comma, or the comma before the last item in a simple list. However, there are certain times when the grammatical style and usage guide actually calls for the use of an Oxford (or serial) comma for clarity’s sake.

As a communications professional, it’s critical you know when—and when not—to use serial commas to adhere to AP style. Let’s dive into the entry on commas so that you can write the clearest possible sentences.

What is an Oxford comma?

Unless you’re a journalist, public relations pro or just a grammar geek, you might be asking yourself, “what is an Oxford comma?” People either love them and use them, hate them and don’t use them, or have no idea what the heck they even are. An Oxford comma can be defined as such:

“a comma used after the penultimate item in a list of three or more items, before ‘and’ or ‘or’.”

Oxford comma example:
• She goes to school, plays league soccer, and takes private dance lessons.

In the example sentence, the comma between “soccer” and “and takes ...” would be the Oxford (or serial, or series, or Harvard) comma. It’s the final comma before the last thing in a list of three-plus items.

Some American writing style guides like The Chicago Manual of Style and The MLA Style Manual mandate the use of serial commas, but the use of the Oxford comma is merely stylistic. So, when does the AP Stylebook say when and when not to use the Oxford comma?

When not to use the Oxford comma, according to AP style:

AP’s guidance is to “not put a comma before the conjunction in most simple series.” Consequently, the comma in the example sentence between “soccer” and “and takes ...” would not be necessary.

Why? Back when people actually read physical newspapers, early printing presses could save paper and ink by omitting these commas unnecessary to the meaning of a sentence.

That said, whenever you’re writing out a list of three or more items, no comma needs to follow the second-to-last item in that list. But the AP’s rules are not hard and fast when it comes to the use of commas in a series.

When to use the Oxford comma, per the AP Stylebook:

To that end, AP style requires that writers include a final comma in a simple series if omitting it could make the meaning unclear. As is always the case with the Stylebook’s editors, clarity remains key. Consider the following sentence as an example of how omitting the Oxford comma could create a messy, difficult-to-comprehend situation for readers:

“I love my parents, Serena Williams and Bob Marley.”

While it is true that I have an intense feeling of deep affection for the people who brought me into this world as well as arguably the greatest tennis player of all time and the late superstar musician who introduced the world to reggae music, the above sentence (as constructed) could be interpreted to mean that Serena Williams and Bob Marley are my parents. They are obviously not.

Another scenario when an Oxford comma should be used, per AP style, is when an integral element of the series requires a conjunction. My company, for example, is a full-service communications agency leveraging an in-house team of PR professionals, SEO strategists and managers, copywriters, graphic designers, videographers, and web designers and developers. Because there is a conjunction in two different items in that sentence—SEO strategists and managers and web designers and developers—that last comma shows that the “and” between videographers and web designers connects the list together.

The third and final situation in which an Oxford comma should be used, per AP style, is in sentences involving more complex phrases. Say you’re developing a blog post highlighting the crucial factors that go into deciding on an app development company. You might draft the following complicated sentence, which requires an Oxford comma.

“The main points to consider are whether the application works as advertised, whether it has the features consumers demand, and whether it delivers promised cost savings.”

In the app development company blog post example above, the Oxford comma helps make the sentence a bit more readable. In most cases, including the Oxford comma provides an important distinction that aids a reader’s comprehension.

Concluding Oxford Comma Thoughts

While the Oxford comma debate will assuredly rage on, at least you now know how to properly use commas in a series, according to AP style. In summary:

• No Oxford comma in simple lists.
• Use Oxford commas to improve clarity.
• An Oxford comma is necessary when connecting listed items requiring a conjunction.
• Use Oxford commas to improve readability in lengthier, complex series.

As illustrated by the ongoing Oxford comma debate, there can be certain exceptions to some rules, and the AP Stylebook is constantly reviewing and clarifying its guidance. Whether you’re devoted to the Oxford comma or think its inconsistent use is unnecessary, there is value in understanding the right and wrong ways to use Oxford commas.

Drew Albee is Content Development Manager at Comprise.