Serial Comma

Have you ever wondered why it's called the "Oxford comma"? We have the answer to that and many more questions you may have about this controversial punctuation mark.

Mignon Fogarty
6-minute read
Episode #866

The Oxford comma is the comma that goes before the final “and” in a series. For example, if I write “snorts, howls, and guffaws,” if I put a comma after “howls” and before the word “and,” that’s an Oxford comma.

Who called it the ‘Oxford comma’?

It’s also called the serial comma or, rarely, the series comma or the Harvard comma, but the name Oxford comma seems to be the most popular, and it gets that name because it’s the style used by the influential Oxford University Press.

a Google ngram showing that the phrase Oxford comma is slightly more common than serial comma and that series comma and Harvard comma are far less common

The name “Oxford comma” is newer than you might think though. The Oxford English Dictionary shows the first printed use of the term in 1978, although it’s likely it had already been used among editors for at least a few years before then because the example is from an informal history of the Oxford University Press and is talking about the origin of the comma rule. In fact, I found what I believe is an example from 1974 in the Google Books database, although I wasn’t able to see the whole thing. 

By contrast, I found references to the phrase “serial comma” from as far back as 1935 and “series comma” from as far back as 1919.

A screenshot of a Google snippet from a 1974 publication called Housman Society Journal (volume 30, page 8) that includes the phrase "it features the splendid Ofo

Who invented the serial comma?

The first style book to recommend using the Oxford comma came out in 1905 in England, and Strunk’s first edition of “The Elements of Style,” which came out a few years later in America, in 1918, also recommended the serial comma.

The 1905 book credited with establishing the Oxford comma rule is titled “Author and Printer: A Guide for Authors, Editors, Printers, Correctors of the Press, Compositors, and Typists” by Francis Howard Collins, and it appears that Collins and his famous biologist/philosopher friend, Herbert Spencer, hashed out the idea of the serial comma in a personal correspondence that Collins later quoted in his book. Collins and Spencer did not give it the name serial comma or Oxford comma, instead, Collins addressed the point in an entry about the word “and” with the heading "and” or “, and.” Here’s what that entry says:

“The late Herbert Spencer allowed me to quote from his letter: — ‘whether to write “black, white, and green,” with the comma after "white," or to leave out the comma and write “black, white and green” — I feel very decidedly in favor of the first. To me, the comma is of value in marking out the component elements of a thought, and where any set of a component of elements are of equal value, they should be punctuated in printing and in speech equally. Evidently therefore in this case, inasmuch as when enumerating these colours black, white, and green, the white is just as much to be emphasized as the other two, it needs the pause after it just as much as the black does.’” (See the manuscript scan at Google Books.)

An interesting but unrelated note is that Spencer is also credited with coining the phrase “survival of the fittest.”

As far as we know, that’s the origin of the serial comma rule. It originally had to do with giving each element equal weight rather than being valued for adding clarity to lists, which is often the argument you hear for using it today.

Now let’s get on to how to use the Oxford comma and when you should.  Ultimately, it’s a style choice.

Do you always have to use serial commas?

Although the British are less likely to use the Oxford comma than Americans (1, 2), primarily it's newspapers that allow writers to omit that final comma (1, 3). For example, although most  American style guides, such as the Chicago Manual of Style and the MLA Style Manual, say to always use the Oxford comma, it’s the Associated Press Styleguide that says it’s OK to leave it out in simple sentences. The theory is that newspapers were often looking to save space when you could only get them in print, and that leaving out the comma in simple sentences is fine because it doesn’t change the meaning or make them harder to understand. 

Consider this sentence: 

When you look at worldwide sales, the top-grossing movies of all time are currently “Avatar,” “Avengers: Endgame” and “Titanic.”

I didn't use a serial comma in that sentence, and it was easy to read, and there wasn't any confusion.

Always use serial commas to prevent confusion

Even in AP style though, you have to use the Oxford comma in more complicated sentences, for example when the items in the list have internal conjunctions (1, 3, 4, 5, 6, 7). Here’s a sentence that could mean different things with and without the final comma: “Rebecca was proud of her new muffin recipes: blueberry, peanut butter and chocolate chip and coconut.”

Without an Oxford comma, you can’t be sure whether the last recipes are peanut butter alone and a combination of chocolate chip and coconut, or peanut butter combined with chocolate chips and then coconut alone. 

You can make the meaning clear in two ways: You can place the final comma after “peanut butter” or after “chocolate chip,” or rewrite the sentence so that there is no ambiguity. 

If you want to say that the combination is peanut butter and chocolate chip, you can write “blueberry, peanut butter and chocolate chip, and coconut,” or if you insist on leaving out the serial comma, you can rewrite the list as “peanut butter and chocolate chip, coconut and blueberry.” But I still think the rewrite is more risky than the sentence with the serial comma because a reader who's just skimming the sentence could be tempted to think that coconut and blueberry is a combination.

Another case where leaving the comma out can be confusing is when the later items in the list can describe an earlier item. An oft-cited example is the made-up book dedication “To my parents, Ayn Rand and God.” A reasonable reader would assume there are at least four entities being thanked: parent #1, parent #2, Ayn Rand, and God; but without the Oxford comma you could also conclude that the two parents are Ayn Rand and God. An Oxford comma clears up any possible confusion: “To my parents, Ayn Rand, and God.”

And even in AP style, you also use an Oxford comma when each element in your series is a phrase, as in “Squiggly wondered whether Aardvark had caught any fish, whether Aardvark would be home for dinner, and whether Aardvark would be in a good mood.” The last two parts of the sentence are so long they benefit from being broken up by a comma.

When a serial comma won’t help

Finally, there are sentences where even an Oxford comma doesn't make the meaning clear. Consider this sentence: “We got to meet Dolly Parton, a singer and a philanthropist.”

Without the serial comma — “We got to meet Dolly Parton, a singer and a philanthropist” — it could mean that Dolly is both a singer and a philanthropist, or that we got to meet three people: Dolly, an unnamed singer, and an unnamed philanthropist.

With the serial comma — “We got to meet Dolly Parton, a singer, and a philanthropist” — it could still mean two different things. It could mean I got to meet three people (Dolly, an unnamed singer, and an unnamed philanthropist), or it could mean I got to meet two people (Dolly, who is a singer, and an unnamed philanthropist).

If you want your meaning to be clear in that sentence, the comma won’t get you there. You need to rewrite it to something like “We got to meet the singer and philanthropist, Dolly Parton.”

The bottom line on serial commas

So, the bottom line is that using the serial comma is a style choice. Most publications except newspapers favor using it all the time, and all publications call for a serial comma when leaving it out could cause confusion. And sometimes sorting out your meaning is just too much for one little comma, and the best option is to rewrite your sentence.

Using the Oxford comma is a style choice

Although the Oxford comma isn't always necessary, I like it, and I use it all the time because I like to have a simple, consistent style instead of trying to decide whether you need something on a case-by-case basis. And I like how it looks. 

But using the Oxford comma is a style choice — a preference — and not an absolute rule of grammar. Even though I’m on #TeamOxfordComma, I’ll die on the hill that Associated Press writers are fine leaving it out of simple sentences. I defend your right to leave out the Oxford comma. But I’m still going to keep using it myself too.


1. Wikipedia contributors. “Serial Comma,” Wikipedia, The Free Encyclopedia, http://en.wikipedia.org/wiki/Serial_comma (accessed March 9, 2022).

2. Quinion, M. “Oxford Comma,” "World Wide Words," http://tinyurl.com/24hncf6 (accessed March 9, 2022).

3. Walsh, B. "Lapsing Into a Comma." Chicago: Contemporary Books, 2004, p. 81.

4. "Serial Commas," The Chicago Manual of Style. Seventeenth Edition. Chicago: University of Chicago Press. Section 6.19. 2017.

5. Shaw, H. "Punctuate It Right." New York: Harper Paperbacks, 1993, p. 77.

6. "comma(,)" The AP Stylebook https://www.apstylebook.com/ap_stylebook/comma-2 (accessed March 10, 2022).

7. The American Heritage Guide to Contemporary Usage and Style. Boston: Houghton Mifflin, 2005, p. 100.

Further Reading

Comma Cause Legal Lad, Adam Freedman, discusses legal cases in which commas determined the outcome.


About the Author

Mignon Fogarty

Mignon Fogarty is the founder of Quick and Dirty Tips and the author of seven books on language, including the New York Times bestseller "Grammar Girl's Quick and Dirty Tips for Better Writing." She is an inductee in the Podcasting Hall of Fame, and the show is a five-time winner of Best Education Podcast in the Podcast Awards. She has appeared as a guest expert on the Oprah Winfrey Show and the Today Show. Her popular LinkedIn Learning courses help people write better to communicate better.