Oxford Comma | Definition, Examples & When to Use

The Oxford comma (also known as the serial comma or Harvard comma) is the use of a comma before the conjunction in a list of three or more items (e.g., the comma before “and” in “paints, brushes, and canvas”). The name comes from the fact that it’s recommended by Oxford University Press.

The Oxford comma is optional—it’s not a grammatical error to leave it out or to include it. Different style guides and publishers have different recommendations about its use, though major style guides recommend using it more often than not.

If you need to follow a particular style guide, check out our quick summary of who recommends the Oxford comma below. If you don’t, the choice is up to you; just write according to your own preference.

Examples of the Oxford comma

The Oxford comma can be used (or left out) in any list of three or more items. This applies whatever those items are (e.g., nouns, verbs, adjectives, longer phrases) and whether the conjunction used is “and” or “or.”

Note that the other commas in the list are not optional. You always need commas between the earlier items in the list, whether or not you add the Oxford comma:

• My hobbies include reading writing hiking and watching movies.
• My hobbies include reading, writing, hiking, and watching movies.
• My hobbies include reading, writing, hiking and watching movies.

But no commas are used in lists of only two items:

• John, and Jane went out for dinner, and to see a concert.
• John and Jane went out for dinner and to see a concert.

Pros and cons of the Oxford comma

Various arguments are used for and against the Oxford comma. The main ones are summarized in the table below.

The argument about ambiguity is the main point of debate. The following section examines it in more detail.

Does the Oxford comma remove ambiguity?

Supporters of the Oxford comma claim that it clears up confusion in two kinds of lists:

• Lists where items could be misread as appositives
• Lists where individual items contain conjunctions

Lists where items could be misread as appositives

Look at the ambiguous list below:

• I spoke to the directors, Jan Sorenson and Tristan Ross.

It’s not clear whether this is a list of three items (“the directors,” “Jan Sorenson,” and “Tristan Ross”) or whether “Jan Sorenson and Tristan Ross” should be read as an appositive—a phrase that tells us who “the directors” are.

Adding the Oxford comma in this case makes it 100% clear that Jan Sorenson and Tristan Ross are not the same people as the directors:

• I spoke to the directors, Jan Sorenson, and Tristan Ross.

But it’s just as easy to find examples where adding the Oxford comma actually makes the list less clear. This occurs when the first item is singular rather than plural:

• I spoke to the director, Jan Sorenson, and Tristan Ross.

Is the director’s name Jan Sorenson, or are they two different people? Here, leaving the comma out actually removes the ambiguity. “Jan Sorenson” can only be read as an appositive if it’s surrounded by commas:

• I spoke to the director, Jan Sorenson and Tristan Ross.

Neither using the comma nor omitting it fixes these problems in all cases, so it can’t be counted as a point for or against the Oxford comma. The ambiguity is more reliably resolved by changing the order of the list items or rephrasing the sentence:

• I spoke to Jan Sorenson, Tristan Ross, and the director.
• I spoke to the directors, as well as to Jan Sorenson and Tristan Ross.

Lists where individual items contain conjunctions

Consider the list below:

• The flavors available include salt and vinegar, sour cream and onion and smoky bacon.

It’s likely that “sour cream and onion” is one flavor, and “smoky bacon” is another. But it’s possible to conclude instead that “sour cream” is one flavor, “onion and smoky bacon” another.

Adding the Oxford comma clarifes which words belong together to describe each flavor:

• The flavors available include salt and vinegar, sour cream and onion, and smoky bacon.

Unlike with the appositives issue, there are no counter-examples where adding the comma creates ambiguity. So this is a clear point in favor of the Oxford comma.

Using the Oxford comma on a case-by-case basis

A third point of view is that you shouldn’t always add or always omit the Oxford comma but rather be flexible: add it when it helps to resolve ambiguity, and otherwise leave it out.

This has some clear advantages. There are cases where the extra comma improves clarity and cases where it creates problems, so flexibility in its use is helpful.

But it also has some potential disadvantages. If you follow one style or the other consistently, an attentive reader will notice any exceptions and understand that they’re deliberate. But if you mix the two styles, your text may just appear inconsistent to the reader.

Who recommends the Oxford comma?

Different style guides, publishers, and language authorities have different stances on the Oxford comma. Some recommend or require it, some advise against it, and some suggest being flexible.

Most major style guides, especially academic ones, do recommend the Oxford comma. Journalistic style guides are less likely to be in favor, since the extra comma takes up space. And the Oxford comma is generally less common in UK English than US English.

Here on the Scribbr Knowledge Base, we aim to use the Oxford comma consistently in our articles. But in our Proofreading & Editing service, we follow the customer’s lead, unless they indicate that they’re following APA Style.

The table summarizes the recommendations of various prominent language authorities.

Lists with semicolons instead of commas

Another way to punctuate complex lists (lists where individual items include conjunctions or commas) is to use semicolons instead of commas between the items. When semicolons are used, there is always a semicolon before the final item. Omitting it is an error.

This approach is best when a list might otherwise be hard to read.

The list above is grammatically correct but quite difficult to parse. Individual items in the list contain commas, conjunctions, and lists of their own. On first reading, it’s hard to tell where one item ends and the next begins. Using semicolons instead makes it easier.

Here, the lists within the list still use commas, but the larger list is divided using semicolons. This makes the sentence easier to parse (although it could certainly still be simplified).

Exception: No comma before an ampersand (&)

In one case, even style guides that normally recommend the Oxford comma tend to say that it shouldn’t be used. This is when the ampersand symbol (&) is used instead of the word “and.” In such cases, the normal approach is to leave the comma out:

• Definition, Examples, & Synonyms
• Definition, Examples & Synonyms

Note that in academic writing, you should normally spell out the word “and” in full anyway. Using an ampersand instead in the main text is considered quite informal. So this issue won’t come up very often.

But some citation styles do require the use of ampersands between author names in in-text citations or reference lists. One of these, APA Style, actually requires the Oxford comma even when the ampersand is used, so bear in mind that this rule is not universal.

Other interesting language articles

If you want to know more about commonly confused words, definitions, common mistakes, and differences between US and UK spellings, make sure to check out some of our other language articles with explanations, examples, and quizzes.

Frequently asked questions

Is the Oxford comma necessary?

The Oxford comma (a comma placed before the final item in a list of three or more items) is optional. It is not an error to leave it out. “Salt, pepper, and vinegar” and “salt, pepper and vinegar” are both grammatically correct.

Different style guides have different recommendations about using it. Most academic style guides (e.g., APA, MLA, Chicago) recommend using the Oxford comma consistently, so this is typically the best approach in academic writing.

Note that the earlier commas in a list are not optional: “salt pepper and vinegar” is not grammatically correct.

Do you put a comma before “and” in a list?

The comma before “and” (or comma before “or”) at the end of a list is optional. It’s referred to as an Oxford comma or serial comma. Most academic style guides recommend adding it (“salt, pepper, and paprika”). But it’s also not a grammatical error to write a list without it (“salt, pepper and paprika”). Some authorities, such as the AP Stylebook, do recommend leaving out the comma.

The Oxford comma tends to improve the clarity of lists, especially complex lists, by showing clearly where one list item ends and another begins. In academic writing, it’s recommended to use it.

What is a serial comma?

The serial comma is a comma that comes before the final item in a list of three or more items. It comes before the conjunction (“and” or “or”): “John, Mandy, and Lupita.” Without the serial comma, the same phrase would be “John, Mandy and Lupita.”

The serial comma is optional; different style guides have different recommendations. But most academic style guides do recommend using it consistently.

The serial comma is also called the Oxford comma or the Harvard comma.

What’s the difference between the serial comma and the Oxford comma?

There’s no difference between the serial comma and the Oxford comma. They’re two different names for the same thing: a comma before the conjunction (“and” or “or”) in a list of three or more items (e.g., “ham, cheese, and tomato”).

The Oxford comma or serial comma is optional but recommended by most academic style guides. It’s sometimes also called the Harvard comma.

Do I need to use the serial (Oxford) comma in APA Style?

Yes, APA language guidelines state that you should always use the serial comma (aka Oxford comma) in your writing.

This means including a comma before the word “and” at the end of a list of three or more items: “spelling, grammar, and punctuation.” Doing this consistently tends to make your lists less ambiguous.