What Is the Serial Comma?

The serial comma, also known as the Oxford comma, is the final comma in a list of items, placed before 'and' or 'or'. Its use can clarify meaning, preventing misinterpretation. For example, "I love my parents, Lady Gaga, and Humpty Dumpty" distinguishes the individuals more clearly. How does this tiny punctuation mark impact reading and writing? Join the conversation on its nuanced role.
Daniel Liden
Daniel Liden

A serial comma is a comma placed just before a coordinating conjunction, such as "and" or "or," in a list. For example, the list "apples, oranges, and pears" contains the serial comma while "apples, oranges and pears" does not. Placing a comma before the coordinating conjunction is a particularly common practice in American English, though it is often omitted in newspaper articles. It is used less commonly in British English and is actually considered grammatically incorrect in some non-English languages. This comma is also, at times, referred to as the Oxford comma, the Harvard comma, or the series comma.

The use of the serial comma can lead to ambiguity in some cases but can actually clear up ambiguity in others. Problems with ambiguity usually arise because of similarities to appositive phrases, as it may be difficult to tell for sure if the writer is adding a new item to the list or adding detail to a previous item. The list "my brother, Andy, and Dave" is ambiguous because "Andy" may be the brother's name or may be an entirely different person. There is, however, no ambiguity when the list is presented as "my brother, Andy and Dave," as commas would be used on both sides of "Andy" if the name were, indeed, an appositive.

Also known as the Harvard comma, the serial comma is used in a list before a coordinating conjunction.
Also known as the Harvard comma, the serial comma is used in a list before a coordinating conjunction.

Omitting the serial comma is not always less ambiguous and can, in fact, also lead to ambiguity in some situations. If the above list were changed to "my brothers, Andy and Dave," ambiguity now exists because "Andy and Dave" might be the brothers or they might be two people other than the brothers. Formulating the list as "my brothers, Andy, and Dave" resolves this ambiguity as the serial comma indicates that the structure is a list and not an appositive phrase. When either use or omission of the serial comma can cause clear ambiguity, it tends to be better to follow the structure that does not, in fact, make the list difficult to understand.

In many cases, the choice to use or omit the serial comma simply comes down to personal preference. Some style guides say it's better to use it while others say it's better to omit it. When writing for a particular publication, however, it is generally necessary to subscribe to the style guide followed by all of the publication's writers. As such, it is important to check with style guides or editors about comma usage before submitting written work for publication.

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Discussion Comments


When it comes to serial commas, I just follow the common sense rule. If it sounds like it needs one in order for the correct meaning to come across, then I use it. If not, then I leave it out.

I do the same when determining if I need to use a comma before “whether.” In this case, I also try to determine if someone would normally pause before the word when reading it, and if so, then I use it.

A lot of times, if you have a compound sentence joined by “and,” then you don't really have a detectible pause. That prompts me to leave out the serial comma. However, if you are using “but” or “yet,” you will often need a pause there to reflect what someone reading aloud would do.


I have always used a comma and a conjunction between two full sentences, so I was surprised to learn that this was not the practice at my local newspaper when I started working there. I had written my first article, and the editor had given it back to me with red marks through all of my serial commas.

I asked him why he did this, and he told me that newspaper writing is supposed to be efficient. We are expected to get to the point quickly without a lot of fanfare or fancy punctuation. Can you believe that he called a serial comma fancy?

I had to stop using the commas in order to keep my job. To this day, though, it just feels wrong not to put the comma in before “and” or “but.”


@kylee07drg – I would love for the serial comma to be the norm once more. However, in a culture that increasingly uses abbreviations as young people shorten words in texts and emails, can we really expect them to actually add something for clarification?

I am seeing more and more text messages and emails that lack capitalization and punctuation altogether. I might just have a heart attack if I saw one full of serial commas used properly!

I do think that omitting it, even if told to do so by style guides, shows a touch of laziness. If someone can get away with eliminating even a chore as small as including a serial comma, they often do.


I learned elementary grammar in the eighties, and back then, everyone seemed to follow the serial comma rule. We were taught to always use it when a sentence included three or more items in a list or if we were writing a compound sentence.

It saddens me that the use of the serial comma has lessened so much. I think it is very necessary and proper. When I read a sentence that skips its usage, I feel like the writer just didn't care to take the time to put the comma in the sentence.

Does anyone else feel strongly about keeping the serial comma in sentences? I feel like our children should be trained to use it, because it clarifies meanings and organizes things well.


@MrsWinslow - When you do read over your work and you're considering whether to use a comma before "and" or some other question, remember that changing the punctuation isn't the only option. You can also reword the sentence.

Let's take the example above: "my brother, Andy, and Dave." Let's say that you are using the Oxford comma and let's also stipulate that Andy is, in fact, your (only) brother. (If you have several brothers, then it would be correct to write "my brother Andy and Dave," but that's a whole other can of worms."

What you could say instead is "Dave and my brother, Andy." Problem solved! If there are three people involved -- that is, if Andy and your brother are separate people -- you can write "Andy, Dave, and my brother."


I had never considered the possibility that *using* the serial comma could cause confusion! I tend to be on the comma-happy side, I suppose, and I'm a fan of the serial comma.

It's important t note that even if the style guide says not to use it automatically, you should of course use it when it presents confusion. So really, you always, always need to read over your work carefully to see if there might be more than one way to read it and adjust accordingly.

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    • Also known as the Harvard comma, the serial comma is used in a list before a coordinating conjunction.
      By: jStock
      Also known as the Harvard comma, the serial comma is used in a list before a coordinating conjunction.