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Rams Write: Oxford Comma

Here you'll find a student-generated guide to writing and composition.


The Oxford comma is a comma that is used when writing a list of items. It appears after the second to last item in the list, before the final "and" or "or." Proper use of the comma in American English is mandatory for equal representation and understanding of ideas. In business, legal, technical, and even creative writing, the Oxford comma can clarify the true meaning of a sentence. 

History of the Oxford Comma

The Oxford comma did not actually originate at Oxford University in England. One can trace its origin in English guides from the early 20th century. The Oxford comma is "correct" in American Standard English but does not exist in other languages, nor is it mandatory in British or International English.

Real World Consequences

Sometimes leaving out an Oxford comma can lead to bigger issues. A simple syntax error in a dairy truck driving description was the start for a ten million dollar lawsuit.

The union contract stated overtime pay would not be given for “the canning, processing, preserving, freezing, drying, marketing, storing, and packing for shipment or distribution of agriculture produce.” The ambiguity of the "or" in relation to packing for shipment or distribution of agriculture produce had some drivers wondering if those distributing but not packaging were legally eligible for overtime. Adding a comma after "shipment" would have clarified the meaning. 

To avoid this issue, the Legislative Drafting Manual warns lawyers and legislators that commas in general are “the most misused and misunderstood punctuation marks in legal drafting, and, perhaps, the English language."


Not using an Oxford comma can create confusing lists and descriptions and lead to combining multiple things that should not be combined.

Example 1

Incorrect: The job involves routine work like detailing, mending, painting and serving customers.

Correct: The job involves routine work like detailing, mending, painting, and serving customers.
Explanation: In the first sentence, the reader may be confused about if the job involves painting customers. An Oxford comma removes that confusion. 

Example 2

Incorrect: Their favorite movies include action, drama, romance and comedy.

Correct: Their favorite movies include action, drama, romance, and comedy.
Explanation: In the second sentence, the reader can see each movie genre as separate. Without an oxford comma, one may believe that the individual likes movies that are simultaneously romantic and comedic. 

Example 3

Incorrect: For the lab, we need hydrogen peroxide, calcium, rubidium and distilled water. 

Correct: For the lab, we need hydrogen peroxide, calcium, rubidium, and distilled water. 

Explanation: Cornell University's Engineering Communication help page states clearly that there is a danger combining rubidium and distilled water. The Oxford comma clarifies that both are needed, but not separately, not mixed together. 

Example 4

Incorrect: Proposed modifications include adding a chain tensioner to minimize chain slack, adding rib supports to prevent flexion of the support platform and using stronger materials to minimize compliance between individual components.

Correct: Proposed modifications include adding a chain tensioner to minimize chain slack, adding rib supports to prevent flexion of the support platform, and using stronger materials to minimize compliance between individual components. 

Explanation: In technical writing, especially in the detail heavy world of science and engineering, Oxford commas are a requirement to understand things clearly. 

This page was created by/ MLA Citations

Spring 2020

Victoria Bailey, Project Intern, Framingham State U (2021)

Spring 2019

Jed Palmer, Framingham State U (2021)

Works Cited

Comdesres, Jasso Lamberg. "Revealed: The true history of the Oxford comma."  Business Insider,

Engineering Communications Program. Cornell University. "Serial Comma/ Oxford Comma,"

Farrick, Ryan J. "A Missing Oxford Comma Could Cost Oakhurst Dairy $10m." Legal Reader, 22 March 2017,

Vox. "The Oxford comma's unlikely origin." YouTube, 17 June 2016,