The comma before "and" in a list — called the Oxford comma or serial comma — is one of the most debated punctuation rules in English. Style guides disagree, writers have strong opinions, and a single missing comma once cost a Maine dairy company $5 million in an overtime lawsuit. Here's everything you need to know, with clear examples for each scenario.
What Is the Oxford Comma?
The Oxford comma is the comma placed immediately before the coordinating conjunction (usually "and" or "or") in a list of three or more items. Example with Oxford comma: "I packed a sandwich, an apple, and a cookie." Without: "I packed a sandwich, an apple and a cookie."
When the Oxford Comma Is Required
To prevent ambiguity. This is the strongest argument for always using it. Consider: "I'd like to thank my parents, Oprah and God." Without the Oxford comma, this reads as if your parents are Oprah and God. Add the comma — "my parents, Oprah, and God" — and the meaning is clear.
In complex lists: "The report covers revenue projections for Q3, hiring plans and retention strategies, and the new product launch." Without the Oxford comma, "hiring plans and retention strategies" reads as a single item when it may not be.
When items contain internal "and": "The menu offers ham and eggs, biscuits and gravy, and pancakes." Without the final comma, the last two items blur together.
When the Oxford Comma Is Optional (or Discouraged)
Journalism (AP Style): The Associated Press Stylebook, used by most newspapers and magazines, advises against the Oxford comma. Journalists argue it saves space and that context usually clarifies meaning. "The flag is red, white and blue" — no ambiguity here.
Simple, unambiguous lists: "I need to buy milk, bread and butter." No reasonable reader would misread this. The Oxford comma here is a matter of preference.
British English generally: Most British style guides (The Guardian, The Economist, The Times) omit the Oxford comma unless needed for clarity. The University of Oxford style guide, ironically, recommends against it — despite the name.
Style Guide Positions
| Style Guide | Position |
|---|---|
| Chicago Manual of Style | Required |
| MLA (academic writing) | Required |
| APA (social sciences) | Required |
| AP Style (journalism) | Omit unless needed for clarity |
| The New York Times | Generally omit |
| Oxford University Press | Required (hence the name) |
The $5 Million Comma: A Cautionary Tale
In 2014, a Maine dairy company settled an overtime lawsuit for $5 million because a state law omitted an Oxford comma. The law listed activities exempt from overtime pay: "the canning, processing, preserving, freezing, drying, marketing, storing, packing for shipment or distribution of" agricultural products. The absence of a comma before "or distribution" created ambiguity about whether "packing for shipment or distribution" was one activity or two. The court ruled in favor of the drivers, who argued that "distribution" was a separate activity not covered by the exemption. One missing comma cost $5 million.
Practical Recommendation
If you're writing for a publication or institution, follow their style guide. For everything else — emails, reports, blog posts, personal writing — use the Oxford comma consistently. It costs you nothing, never causes confusion, and occasionally prevents expensive misunderstandings. Consistency matters more than which rule you choose.