What Is the Oxford Comma?

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Punctuation, those little dots and squiggles in between the curving forms of letters, can sometimes seem an aesthetic sensibility until your English teacher drowns your paper in blood-red ink. However, one instance of an improperly used comma led to more than just classroom criticism, it led to thousands of dollars at stake and the birth of one specific, and very important punctuation mark – the Oxford comma.

In this article, we will discuss what the Oxford comma is, its importance, and examples. We’ll be referencing the infamous lawsuit that led to greater awareness of the Oxford comma and discussing differing arguments for its use. By the end of this article, you’ll know this tiny dot inside and out!

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history of the oxford comma

History of the Comma

Before diving into the highly specific Oxford comma, let’s explore the origins of the original comma. In the 3rd century BCE, Aristophanes, an Ancient Greek grammarian, utilized dots at different levels to separate verses within his writing, typically read aloud. He used the Ancient Greek word “κόμμα” (komma) to describe these dots.

This “komma” fell out of practice with the decreased prominence of oral literature. However, in the 1490s, when printing books was on the rise, Aldus Manutius changed the face of English grammar. He converted the slash (/), which had been used to signify pauses in the middle of a sentence, into a dot with a rounded tail. This is the comma we know today.

Modern commas are used to separate words, phrases, and clauses. (Note my use of the Oxford in the previous sentence!) Think of it like a pause to clarify the complicated moving parts in a sentence. Now that you know all about the comma, let’s explore a specific type -- the Oxford comma.

Looking into the Oxford comma because you’re starting an essay for a college application? Don’t forget to look at our blog on what to write in your college essay!

Technical Definition of the Oxford Comma

The technical definition for the Oxford comma, according to Oxford languages, is “a comma used after the penultimate item in a list of three or more items, before ‘and’ or ‘or’.” In simpler words, it’s the comma you put at the end of a list of things.

The Oxford comma is technically called a “serial comma” or “series comma” and it has been known by other names such as the “Harvard comma.” However, after its required use by the Oxford Printing Press, the serial comma has become more widely known as the Oxford comma.


Here are some examples of an Oxford comma being used in a sentence:

  • I love my parents, my fish, and my dog.
  • I ate a sandwich, pasta, grapes, and cookies.

The Oxford comma is the last comma in each of the above sentences. It more clearly separates the last item in each list. Here is what the sentences look like without an Oxford comma.

  • I love my parents, my fish and my dog.
  • I had a sandwich, orange juice, pasta and cookies.

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importance of the oxford comma


So why is the Oxford comma such a big deal? For many people, it may seem like the English language is just trying to complicate things by unnecessarily specifying different types of commas when, in reality, their function is the same as a “normal” comma.

The purpose of the Oxford comma is to avoid ambiguity. Without using an Oxford comma, confusion may arise about the nature of items in a list. Here is the same sentence from before.

  • I love my parents, my fish and my dog.

Without a comma before “and”, the speaker could be interpreted as having parents who are animals. The fish and dog might be further specifying who their parents are. With an Oxford comma, it is abundantly clear that the speaker is referring to three separate things that they love: their parents, their fish, and their dog.

  • I love my parents, my fish, and my dog.

However, Oxford commas, despite their efficiency in addressing potential ambiguities, are not required worldwide. Historically, it has been a British practice, while American publishing houses have left it out of their sentences.

All of this changed when dairy drivers in Maine sued for $10 million.

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Maine Lawsuit

In 2014, Oakhurst Dairy, a company specializing in dairy products as well as some juices, was sued by its truck drivers for $10 million. The dispute was about overtime payment and whether the Maine law on overtime pay applied to them.

Within Maine’s labor laws, one sentence was at the heart of this controversy. It details which tasks are exempt from receiving overtime pay, meaning that Oakhurst Dairy would not have to pay its drivers extra for the following tasks:

“The canning, processing, preserving, freezing, drying, marketing, storing, packing for shipment or distribution of:

  • “(1) Agricultural produce;
  • “(2) Meat and fish products; and
  • “(3) Perishable foods.”

Let’s look closely at “packing for shipment or distribution.” Notice how there is no comma before the word “or.” This means that shipment and distribution could be seen as either two separate tasks or one singular task, but it’s not clarified which.

The dairy drivers argued that because of the lack of a comma between “shipment” and “distribution,” shipping and distribution were seen as a single act. Therefore, since they didn’t do any packing, they should not have been exempt from overtime pay. Only laborers who had done both shipping and packing couldn’t receive overtime pay.

After the dairy drivers took Oakhurst Dairy to court, their company eventually settled the lawsuit for $5 million.

The Maine labor laws have since been edited to include semi-colons after every item in the list.

oxford comma use

When to Use the Oxford Comma

Since the Oxford Comma cost a company $5 million, you might think that all style guides have adopted the Oxford comma as a requirement. After all, its purpose is specifically to prevent ambiguity, and add clarity and precision to the use of written English.

In fact, there is still heated debate about the use of the Oxford comma, though it has since died down after the lawsuit. Still, depending on the style guide you’re using, it may be wrong to use an Oxford comma.

Style Guides Which Use the Oxford Comma

  • Oxford Style Manual
  • Chicago Manual
  • MLA Handbook
  • Modern Humanities Research Association

Style Guides Which Don’t Use the Oxford Comma

  • University of Oxford Style Guide
  • Associated Press Stylebook
  • Cambridge University Press

While the Oxford comma has historically been a British practice, its use has become more and more popular with American readers. In fact, the Oxford comma is almost always used in American English now, and only certain style guides advocate for its absence.

Even then, as with the case of the Associated Press Stylebook, an Oxford comma can still be used if confusion would be created in its absence. The style guide, however, doesn’t recommend it in every sentence with three or more items.

So why do some style guides use it and others don’t?

Browse our blog for more information on college-related content!

pros and cons fo the oxford comma

Pros and Cons of the Oxford Comma

Now, let’s do a deep dive into the pros and cons of using the Oxford comma!


  • Clarity. As demonstrated in the section on the importance of the Oxford Comma, its entire role is to prevent potential ambiguity. In lists of three or more terms, it can become confusing which items are being referred to as one or two separate things. The Oxford comma ensures that each final item is seen as a distinct item.
  • Standardization. It has now become the trend to use Oxford commas, whether you’re in the UK, the U.S., or a different part of the world. After the Maine lawsuit, proponents for the Oxford comma could point directly to the financial consequences of not utilizing the comma. When in doubt, your style guide is probably unopposed to its use.
  • Equal Weight. In the Modern Humanities Research Association (MHRA) style guide, they justify the use of the Oxford comma in order to give “equal weight to each enumerated element”. This means that each separate item is not grouped with another and given a distinct role within the list.


  • Redundancy. Even though the Oxford comma has demonstrated its ability to resolve ambiguity, some style guides still reject its use. They argue that it is redundant and its use is overly pedantic. In addition, back when physical newspapers were still being produced on copy desks, the character limit made many publishing houses wary of using an Oxford comma.

Final Say

Whether you’re an elite member of the Oxford academic circles or an American college student just wanting to get through writing a paper, the Oxford comma is ultimately just a matter of personal preference. If your professor requires your essay to adhere to a certain style guide, make sure to always follow that style guide’s rules on the Oxford comma.

If your professor’s rules are more lax, it often makes no difference whether or not an Oxford comma is used. The Maine lawsuit and the parent examples are two extreme cases where the lack of the Oxford comma does create ambiguity. Most of the time, it won’t.

Remember, this is specific to the Oxford comma, which has a controversial history. For other punctuation, adhere to style guides as they may have clearer grammar rules.

The one thing I would recommend, especially for college students, is to check with your professor. If, for some reason, this isn’t possible, it can’t hurt to add that extra comma. Who knows? It might just end up saving you $5 million.

oxford comma in English

Frequently Asked Questions About the Oxford Comma

Why is the so-called Oxford comma known as a serial comma?

The technical name for an Oxford comma is a serial comma because of its function in a list or series of three or more items. The Oxford comma only got its most commonly used name after Horace Hart, a printer for the Oxford University Press, who implemented it into the Oxford Style Guide in 1905. The Oxford University Press has since required its use.

Is it grammatically correct to use the Oxford comma?

There is no hard and fast rule on what is grammatically correct. Grammar rules on the Oxford comma are a case-by-case basis depending upon each publishing house style. While one style might require separating items with a final comma, others may not.

Should I use the Oxford comma in my college application essay?

A college application essay is your chance to express yourself through writing. Whether that requires the use of the Oxford comma or not is completely your choice. If you still have doubts, ask someone to look over the sentence in question and see if the separation of items is clear to them.

Feel like you’ve got a good grasp on the Oxford comma and want to explore some other comma content? Explore our blog on the comma splice to enhance your technical writing skills!