The Oxford comma: what it is, when it matters, and why most books use it
The Oxford comma is the comma before "and" or "or" at the end of a list: "red, white, and blue." Whether to use it is a style choice, not a grammar rule. But for book authors the choice is mostly made for you: The Chicago Manual of Style, the standard for most US book publishing, requires it. Here is what it does, when leaving it out causes trouble, and how to stay consistent.
What it is
In a list of three or more items, the Oxford comma is the one just before the final "and" or "or":
- With it: We packed snacks, maps, and a first aid kit.
- Without it: We packed snacks, maps and a first aid kit.
Its plain name is the serial (or series) comma. According to the Chicago Manual of Style's blog, CMOS Shop Talk, many people know it as the Oxford comma because of the long-standing house style of Oxford University Press.
When it changes the meaning
Most of the time, the list is clear either way. The comma earns its place when the last two items could be read as describing the first. These are our own examples:
| Without the Oxford comma | How it can be misread | With it |
|---|---|---|
| I thanked my parents, Oprah and the Pope. | Your parents are Oprah and the Pope | I thanked my parents, Oprah, and the Pope. |
| The book is dedicated to my mentors, Ana and Luis. | Ana and Luis are your mentors (maybe true, maybe not) | The book is dedicated to my mentors, Ana, and Luis. |
| We interviewed two founders, a coach and an investor. | The founders are a coach and an investor | We interviewed two founders, a coach, and an investor. |
Examples written by Scribe Media. Sometimes the comma itself creates a different ambiguity; if a list reads awkwardly either way, rewrite the sentence.
Who uses it, and who does not
- The Chicago Manual of Style: requires it. CMOS Shop Talk says most book publishers and their editors swear by it, and that Chicago requires it, citing section 6.19.
- The Associated Press Stylebook: mostly leaves it out. CMOS Shop Talk notes AP says to use it only where its absence might lead to ambiguity. That is why newspapers and many news sites rarely use it.
- Oxford University Press: uses it, hence the name. Its style guide notes the style is used by many other publishers in the UK and elsewhere.
What to do in your book
- Use it, unless your publisher says otherwise. Book publishing in the US generally follows Chicago, so the serial comma is the expected default.
- Be consistent. Readers notice a book that uses it on one page and drops it on the next more than they notice either choice.
- Put it on your style sheet. A style sheet is the list of choices your editor and proofreader follow; this belongs at the top. See what a copy editor does.
- Rewrite when neither version is clear. If a list can be misread with or without the comma, change the order or break it into two sentences.
Search your manuscript for ", and " and " and " in lists during your own revision; see how to edit your own book for the full consistency pass.
Start here: decide yes or no, write it at the top of your style sheet, and search the first chapter to check you have been consistent so far.
Common questions
What is the Oxford comma?
The comma before the last item in a list of three or more, just before "and" or "or": "red, white, and blue." It is also called the serial or series comma. The name comes from Oxford University Press, whose house style has long used it.
Is the Oxford comma correct?
Both styles are correct; it is a style choice, not a grammar rule. The Chicago Manual of Style requires it, which is why most book publishers use it. The Associated Press Stylebook, used by most newspapers, uses it only when leaving it out would cause confusion.
Should I use the Oxford comma in my book?
For a book, usually yes. Chicago is the standard style for most US book publishing, and it requires the serial comma. Whatever you choose, use it the same way throughout, and note it on your style sheet so your editor follows it too.
What is an example of the Oxford comma changing meaning?
"I thanked my parents, Oprah and the Pope" can read as if your parents are Oprah and the Pope. "I thanked my parents, Oprah, and the Pope" makes clear there are four people. That ambiguity is the main argument for using it.
Does the Oxford comma go before "or"?
Yes, if you use it at all: "tea, coffee, or water." It goes before the conjunction that ends the list, whether that is "and" or "or."
Sources: CMOS Shop Talk (The Chicago Manual of Style's blog), Russell Harper, Oxford, Chicago, and the Serial Comma (Chicago requires it, CMOS 6.19; most book publishers use it; AP uses it only where its absence might cause ambiguity; Oxford University Press origin and New Hart's Rules), read November 1, 2026. The examples and guidance were written by Scribe Media. Published by Scribe Media.