What Is the Serial Comma? (and Why You Should Use It)

Writers, let’s talk about everyone’s favorite punctuation mark to hate on: the serial comma (aka the Oxford or series comma). What is the serial comma? Why should you use it?

First, the boring definition. Then, an illustration of just how off the rails your prose could go if you leave it out.

Before you throw the rotten tomatoes my way, here’s how The Chicago Manual of Style defines a serial comma:

Items in a series are normally separated by commas . . . When a conjunction joins the last two elements in a series of three or more, a comma—known as the serial or series comma or the Oxford comma—should appear before the conjunction. Chicago strongly recommends this widely practiced usage, blessed by Fowler and other authorities (see bibliog. 1.2), since it prevents ambiguity. If the last element consists of a pair joined by and, the pair should still be preceded by a serial comma and the first and (as in the last two examples below). (CMOS18, 6.19)

The Serial Comma Prevents Ambiguity

There are so many opinions about the serial comma, but ultimately, for me, using it all comes down to something so neatly encapsulated in Chicago’s explanation: the serial comma “prevents ambiguity.”

“Preventing ambiguity” is the heart of an editor’s job, and writing without ambiguity is the ultimate goal for a writer. Or it should be. Because what good is writing something if a reader misunderstands the intended meaning behind your words?

As an example, consider this sentence:

“The highlights of his waning administration include encounters with Rudy Giuliani, a healthcare disaster and a dildo collector.”     <—— Now put a comma after “disaster” and see what happens.

😅😉

Ahem. Case rested.

Author Intent Matters

The intent behind the sentence was to list three things “he” encountered. However, without the serial comma in that series, the final clause instead applies to “Rudy Giuliani” as a modifier.

Instead, the sentence should be: “The highlights of his waning administration include encounters with Rudy Giuliani, a healthcare disaster, and a dildo collector.”

And another example (louder for the people in the back):

“She posted pictures of her parents, the president and the vice president.”

Are her parents the prez and vice prez? Or did the author intend to say that she posted three pictures—one of her parents, one of the president, one of the vice president?

Nobody knows . . . because we don’t have a comma where it should be to guide us.

So, yeah. Use it or lose it, as they say. (Full understanding, that is.)

But as with every “rule,” your book is your book. If you’re morally opposed to that tiny bit of misunderstanding-busting punctuation, by all means, leave it out.

Just make sure to structure your prose well enough that your sentences don’t leave room for such, ahem, misinterpretation.