Serial comma

Serial CommaPhoto cred: Paul Trienekens on Unsplash

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Nothing ignites fire in the gut of righteous grammar geeks more than the serial—aka Oxford—comma.

Why is that?

Maybe you heard about the Maine dairy-truck drivers’ recent legal victory that hinged on a comma—actually, the lack of a comma. The truck drivers won an appeal against their employer, Oakhurst Dairy, regarding overtime pay. Last week Oakhurst settled the case and paid up.

What’s a serial/Oxford comma? It’s the final comma in a list of things in a sentence. As in:

Marketers love clever creative, remarkable ROI, and respect.

The Oxford comma is that comma after “ROI.”

Here’s a well-known explanation of how the Oxford comma adds critical clarity:

Serial Comma


One Morning in Maine

The Maine dairy story is a convoluted story, as most law-related stories are. Here are the basics:

  • In 2014, three truck drivers sued the dairy for what they said was four years’ worth of overtime pay owed to them for deliveries they’d made.
  • Oakhurst Dairy said NOPE, citing a law that lists distribution of dairy products as one of the activities ineligible for overtime pay.
  • Maine state law at the time stated that workers are not entitled to overtime pay for: “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.”
  • Aha…! the lawyer for the truck drivers said.
  • Without a comma after “shipment,” it’s the packing “for shipment or distribution” that’s not eligible for overtime—not the distribution itself. Only with a comma would “distribution” have been included as one of the series of activities ineligible for overtime.
  • So: the law does not apply to the deliveries the drivers made. Pay up, Oakhurst.
  • The court (the US Court of Appeals for the First Circuit) agreed—and took 29 pages to say as much. Oxford comma enthusiasts high-fived!
  • Earlier this month, Oakhurst Dairy settled, agreeing to pay $5 million to the drivers.
  • The case of the dairy-truck drivers’ comma has got several things going for it, says former New Yorker copyeditor Mary Norris.
  • It’s got a David-and-Goliath showdown between the little guys and the corporate overlord.
  • It’s got “guys driving around in trucks with copies of Strunk & White in the glove box.”
  • And, of course, it’s… wait for it… got milk.
  • But it’s also got something else we love: It’s got people arguing over grammar.

People love love looooove to argue over grammar

And we especially love to argue over the polarizing Oxford comma: defended as a beacon of clarity, derided as an unnecessary pest.

Why does something as pedantic and ordinary as grammar ignite raging debate—both in Maine and in the rest of world? Even when there isn’t actual money at stake?

And more broadly: Why do some of us love to correct the grammar of others? Love to sharpen our grammar chops on the soft underbelly of those unfortunates who might use literally to mean figuratively? Who misspell lose as loose?

Maybe it has something to do with that word “rules” when it’s paired with “grammar”: Grammar rules seem strict, impenetrable, unyielding.

Where Did the Oxford Comma Come From, and Why Is It So Important?

It's not often that a piece of punctuation makes national headlines, so when one does, you know it must be pretty important.

Recently, the Oxford comma shot into stardom after becoming the crux of a $10 million class-action lawsuit against a Maine dairy company.

The comma in question (or rather, the missing comma in question) gained notoriety due to its absence from a state law. The law declares that overtime rules do not apply to the following: “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.”

With no Oxford comma following packing for shipment, it is unclear whether the law exempts the distribution of the three categories that follow or whether it exempts only the packing of the items in preparation for their shipment or distribution.

Clear as milk? (Get it? Because it's a dairy company?) Learn a bit more about what the Oxford comma is, where it came from, and why it's so important below.

What Is the Oxford Comma?

  • The Oxford comma, also called the serial comma or Harvard comma, is a much-debated piece of punctuation that occurs just before a coordinating conjunction in a series of three or more items.
  • For instance, in the below sentence, the Oxford comma is placed before and:
  • My favorite cheeses are Gouda, Havarti, and Brie.
  • In some style guides, such as that of the Associated Press (AP), the only time an Oxford comma is used is when it is necessary in order to accurately understand the sentence. Here's a popular example of a sentence in which the absence of an Oxford comma results in an inaccurate (and quite humorous) interpretation:
  • “This book is dedicated to my parents, Ayn Rand and God.”
  • Without a comma before and, it appears that the writer is specifying that his or her parents are Ayn Rand and God.
  • While many are passionately in favor of the Oxford comma for this reason, others loathe it, feeling that it interrupts the flow of a sentence and should only be used to avoid ambiguity.

Where Did the Oxford Comma Come From?

Just as there is confusion about its use, there is also confusion about the origin of the Oxford comma.

Aldus Manutius (also known as Aldo Manuzio) was a 15th-century Italian printer who introduced the comma as we know it, as a way to separate things. The word comma comes from the Greek word koptein, which means “to cut off.”

The Oxford comma has been attributed to Horace Hart, printer and controller of the Oxford University Press from 1893 to 1915, who wrote Hart's Rules for Compositors and Readers in 1905 as a style guide for the employees working at the press.

However, at that time, the comma was not called the Oxford comma. In fact, it had no name until Peter Sutcliff referred to the Oxford comma in his 1978 book about the history of the Oxford University Press.

Sutcliff, however, credited F. Howard Collins with introducing the Oxford comma. Collins first mentioned it in his 1912 book, Author & Printer: A Guide for Authors, Editors, Printers, Correctors of the Press, Compositors, and Typists.

Why Is the Oxford Comma Important?

Regardless of who actually invented the Oxford comma, its purpose is to make a sentence clear, unambiguous, and understandable. So why does it also make people enraged, perplexed, and confused?

Many style guides, including the Chicago Manual of Style, American Psychological Association (APA), and American Medical Association (AMA), recommend the use of the Oxford comma to prevent ambiguity.

Yet others, including the AP style guide, Canadian Press (CP) style guide, and (shockingly) the University of Oxford style guide itself, use the Oxford comma only when a sentence could be misinterpreted by the reader without it.

Here's the problem, though, for those who do not consistently use the Oxford comma: when writing a sentence, you don't always realize that what you're writing could be misinterpreted. This is demonstrated quite clearly in the Maine lawsuit case above.

For most people, this ambiguity won't cost you $10 million. But it might cost you clarity, time, or reputation.

  1. Why not use the Oxford comma, just to be safe?
  2. Serial Comma
  3. Image source: keem1201/
See also:  How do words get in the dictionary?

The serial, Harvard, or Oxford comma

I apologize for the intermittent posting the past month; what with the end of summer filling me with the spirit to jam in a bunch of relaxation and the end of summer filling me with a need to jam in a bunch of work that I didn’t do earlier, I’ve had precious little time to write about grammar.

  But admittedly, it was also that my interest in the intricacies of grammar were flagging a bit.  I know that’s not something that many people would lament, this inability of grammar to raise one’s hackles.  In fact, for many prescriptivists, this is something I wish they’d encounter.

  But for me, it was a bit worrisome — especially as I had recently been enjoying a resurgence of interest in syntactic research.

And then I was in a conversation with my mother in which she remarked on some people’s usage of a commas in a list.  Specifically, she didn’t understand why anyone would add a comma after the penultimate item in a list, as in (1); she found it to be greatly preferable to omit it, as in (2).

(1) What sort of fool, imbecile, or moron does the author take me for?
(2) Surely I can read, follow and understand the point without the extra comma!

At that, my grammatical hackles rose!  It was time to discuss the finer points of a negligible grammar point!  Hooray!  A long and boring conversation ensued about why my mother was biased against the comma (she blamed her strict schooling), why I was biased toward the comma (I blamed my raging Anglophilia in my formative years), and why she was bothered so by the presence or absence of such a minor mark (her schooling coupled with her natural proclivity to favor order in the universe).  But the big question our conversation raised — and failed to answer — was this: why is this comma an issue at all?  No one argues that the other commas in a list ought to get the heave-ho, but people are pretty evenly divided over the Oxford comma.  So what’s its deal?

First, a bit of background. The Oxford comma is so called because it is standard in the style guide for the Oxford University Press, and has been for over a hundred years. The Oxford comma is attested in the 1905 edition of the OUP Style Guide, and remains there to this day.  The comma also goes by a few other names.

Those of a less Anglophilic bent can call it the Harvard comma — although as a loyal Princetonian I would never sully my reputation by doing so. Those who seek to remain neutral in such Anglo-American affairs can call it the serial comma.

And those who don’t much care about minor punctuation issues refer to it as “that extra comma” or “that stupid extra comma”, depending on whether or not they use it.

But whatever you call the comma, is it right or wrong? There’re fair arguments on both sides.  One might be concerned about limiting ambiguity. Alas, including the Oxford comma can lead to ambiguity, but omitting it can lead to ambiguity as well.  Consider (3) and (4):

(3a) I own pictures of my friends, Hugh Grant, and Dolly Parton.
(3b) I own pictures of my friends, Hugh Grant and Dolly Parton.

(4a) I am writing to my Congresswoman, Alia Shawkat, and Michael Cera.
(4b) I am writing to my Congresswoman, Alia Shawkat and Michael Cera.

It is clear, thanks to the Oxford comma in (3a) that I am not friends with Hugh Grant or Dolly Parton. In (3b), though, they could potentially be my friends, listed as an appositive phrase, and the sentence is thus somewhat ambiguous.

Deus ex Oxford comma! On the other hand, in (4a), if you don’t know who Alia Shawkat is, then you may reasonably conclude that the commas are intended to indicate an appositive and that Alia Shawkat is my Congresswoman. (4b) is clearer; since Alia Shawkat and Michael Cera can’t both be my Congresswoman, it’s clear that I was constructing a three-item list.

Diabolus ex Oxford comma!  In the first case, the Oxford comma dispels ambiguity, but in the second it induces ambiguity.  So ambiguity doesn’t push us one way or the other.

Okay, so is the comma right or wrong? Well, it depends on who you’re trying to please.  Wikipedia offers a nice list of which style guides say the comma ought to be used and which say it ought not to, and there’re some heavy hitters on both sides.

  Historical usage is also divided: An Exact Diary of the Late Expedition of His Illustrious Highness the Prince of Orange, (now King of Great Britain) from His Palace at the Hague, to His Arrival at White-Hall (1689) uses the comma, but The History of the Rebellions in England, Scotland and Ireland (1691) rebels against it. Others are more irresolute about the comma, occasionally using it, occasionally spurning it; Dud Dudley’s Mettallum Martis (orig. 1665, reprinted 1854) is one such example. This 17th-century indecision continues to the present day.

Oxford, Chicago, and the Serial Comma

What’s in a Name?

Its generic name is the serial (or series) comma, but many people know it by a fancier name: Oxford comma.

The serial comma is the one before and, or, or nor at the end of a series of three or more items. It’s the comma after b in “a, b, and c”—and, incidentally, the comma after the first or in the previous sentence.

Most book publishers (and their editors) swear by it, and CMOS requires it. By clearly demarcating the last two items in a series, the serial comma adds precision.

Many journalists, on the other hand, will tell you it’s rarely necessary. The Associated Press Stylebook says to use it only in cases where its absence might lead to ambiguity. For example, in “a, b, and c and d” (where c and d form a unit), the comma after b is essential.

Whether you use it or not, you may still want to know: Why is it called the Oxford comma?

Oxford’s Claim

Oxford is the oldest university in the English-speaking world and has the second-oldest university press, after Cambridge. Both presses trace their founding to the sixteenth century (the University of Chicago Press, by comparison, was founded in 1890).

Using a Comma before "And" in a Series

  • Writers frequently wonder whether a comma should go before the conjunction and in a list of three or more items. Despite the fact that not all style books agree on this issue, we recommend using a comma after the next-to-last item in a series—the serial (or Oxford or Harvard) comma, as it is called. This recommendation also applies, of course, when the items in a list are joined by the conjunction or.

    See also:  Delete these words to crush redundancy

    The Serial Comma Helps to Prevent a Misreading

    Although many of us were taught not to use a comma before and in a list, today the vast majority of style guides do advocate the use of the serial comma because it can prevent a possible misreading. Consider this sentence, for example:

    • Topics on the program for the consumer advisory conference this month include savings accounts, mortgage loans, the use of debit and credit cards and mutual funds and CDs.

    Without the serial comma, the individual series items are difficult to identify.

    • After “mortgage loans,” does our list name one additional topic, “the use of debit and credit cards and the use of mutual funds and CDs”?
    • Or does it contain two more items, “the use of debit and credit cards” and “mutual funds and CDs”?
    • Or does it contain three more items, “the use of debit and credit cards,” “mutual funds,” and “CDs”?

    With the serial comma added, we can see clearly that we have here a list of four program topics, not two or three:

    Topics on program for the consumer advisory conference meeting this month include savings accounts, mortgage loans, the use of debit and credit cards, and mutual funds and CDs.

    Although such logical precision might seem trivial when we are talking about topics at a conference, it can be absolutely crucial in certain kinds of writing.

    The Serial Comma is Especially Important in Legal Writing

    Take legal documents, for example. The Texas Law Review Manual on Usage, Style, and Editing  insists on the use of the serial comma. In The Lawyer’s Book of Rules for Effective Legal Writing, Thomas R. Haggard says, “The serial comma is essential in legal writing because it promotes clarity” (17).

    Consider this sentence:

    Mrs. Jones left all her money to her three children: Huey, Dewey and Louie.

    Without the serial comma, the sentence does not clearly indicate that each of the three children is to be given an equal share of the inheritance. Quite possibly (especially if Huey were a jerk), Huey would get half the money, and Dewey and Louie would have to split the other half.

    Here’s another example of a sentence in which the omission of the serial comma has a substantive effect on the meaning:

    Mrs. Jones left her money to her children: Sally and Fred Smith, Margaret and John Williams, Betty and Harold Spivey and their children.

    Without the serial comma before the last and, the sentence could be interpreted to mean that only the children of Betty and Harold Spivey are to receive a share of the inheritance and not the children of the other couples. But with the additional comma, the sentence more clearly communicates the idea that the children of all three couples are to receive a share:

    Mrs. Jones left her money to Sally and Fred Smith, Margaret and John Williams, Betty and Harold Spivey, and their children.

    In all kinds of writing, of course, the meaning of the items in a list may be obvious without the serial comma. But we are usually poor judges of our own clarity (or lack thereof). We tend to think we are being clear because we know what we mean to say.

    If we were to write, for example, “The table was covered with gifts, food and flowers,” the meaning might appear to be quite clear without the serial comma.

    But even this seemingly simple and clear sentence could be read two ways:

    • The table may be covered with three different kinds of items: (1) gifts, (2) food, and (3) flowers.
    • Or the table may be covered with gifts, all of which fall into one of two categories—food or flowers.

    Not All Style Books Agree

    It is always wise to check your company’s in-house style manual or the style manual that governs your profession. In the United States, the vast majority of reputable style guides (with the exception of style guides for journalists, such as the well-known manual published by the Associated Press) encourage or even mandate the serial comma.

    We don’t know for certain, but we can suppose that print journalists omit the serial comma because in their profession, saving keystrokes means saving money. Nonetheless, even style guides that generally discourage its use do agree that at times it is necessary for clarity and/or readability.


    Which of these sentences would be improved by the addition of the serial comma?

    1. Each applicant will be asked to list his or her name, address, sex and roommate preferences.
    2. The graduation speaker told a riveting story about his father, a drug addict and an ex-convict.
    3. In the final round of the cooking competition, the contestants had to prepare three different quiches: broccoli, ham and cheese and spinach.
    4. Sunday’s reception will feature a variety of elegant finger sandwiches: cream cheese and pineapple, marinated bell peppers and goat cheese, asparagus and butter and sliced cucumber and mint mayonnaise.
    5. “The woods are lovely, dark and deep.” (Robert Frost, in “Stopping by Woods on a Snowy Evening”)


    1. Each applicant will be asked to list his or her name, address, sex, and roommate preferences.
    2. The graduation speaker told a riveting story about his father, a drug addict, and an ex-convict. [However, if the speaker’s father were, indeed, a drug addict and ex-convict, the sentence would be correct without the serial comma.


    3. In the final round of the cooking competition, the contestants had to prepare three different quiches: broccoli, ham, and cheese and spinach. [Or “In the final round of the cooking contest, the contestants had to prepare three different quiches: broccoli, ham and cheese, and spinach.

      ” The serial comma goes after “ham” if the cheese belongs in the spinach quiche but after “cheese” if the cheese belongs in the ham quiche.]

    4. Sunday’s reception will feature a variety of elegant finger sandwiches: cream cheese and pineapple, marinated bell peppers and goat cheese, asparagus and butter, and sliced cucumber and mint mayonnaise.

    5. This sentence is actually correct without the serial comma. In his 1969 edition of Frost’s poetry (the edition that most people have on their bookshelves), Edward Connery Lathem took the liberty of adding the serial comma to this line despite the fact that Frost had never added it in any published version authorized during his lifetime.

      In Frost’s version (without the serial comma), “dark and deep” are an appositive for “lovely.” The speaker thinks that the woods are lovely precisely because they are dark and deep, giving us insight into the speaker’s state of mind. By adding the serial comma, Lathem changes the meaning of the sentence.

      Instead of a single adjective (“lovely”) with an appositive (“lovely” = “dark and deep”), Lathem’s version suggests that the woods have three separate qualities: they are lovely, they are dark, and they are deep.

      (For a fuller discussion of the problems with the Lathem edition of Frost, see Donald Hall’s “Robert Frost Corrupted” in Breakfast Served Any Time All Day [Ann Arbor: University of Michigan Press, 2004, pages 81 to 99]. An authoritative version of Robert Frost’s poems was published in 1995 by the Library of America.)

    ©2009 Get It Write. Revised 2018.

  • How to use serial commas correctly when writing in English

    The serial comma (also known as the Oxford comma) is a very controversial punctuation mark! It is so controversial that it was recently featured in a news article on the CNN website, ‘Should we give a damn about the Oxford comma?’

    What Is a Serial Comma?

    The Macquarie Dictionary (2017) defines the ‘serial comma’ as:

    The comma used before a conjunction linking the final item in a series, as in Portugal, Spain, and France where the comma after Spain is the serial comma.

    When Do I Use the Serial Comma?

    The simple answer is that in Australia and New Zealand, we don’t routinely make use of the serial comma. That means you definitely don’t put it before every ‘and’ in a list of more than two items. In fact, we only use it when it is necessary for clarity or to avoid confusion.

    Avoiding Ambiguity

    In the following example, the ‘and’ internal to the second-last list item makes it unclear whether the third-listed item should be ‘rate of pay and type of benefits’ or ‘rate of pay’ only, with the fourth-listed item as ‘type of benefits and reported level of support’. Using the serial comma clarifies this:

    Four aspects will be considered: time in classroom, experience, rate of pay and type of benefits, and reported level of support.

    In that example, the distinction might not seem that important. But as the CNN article reports, there have been many court cases over ambiguity caused by the presence or absence of a comma! This was the case for a group of truckers in Maine:

    If you were a trucker reading that union rules deny you overtime pay for ‘the canning, processing, preserving, freezing, drying, marketing, storing, packing for shipment or distribution of agricultural produce,’ would you consider yourself due overtime payment nevertheless for distribution? That is, as opposed to packing things for shipping and distribution?

    Truckers for Oakhurst Dairy in Maine have been granted back overtime pay for having distributed product as opposed to packing it, because though the writers of the contract meant that overtime would not be granted for distribution either, this is not clear when there is no comma after shipment. The drivers’ lawyer has successfully argued that the contract appears to stipulate that overtime won’t be granted for, only, the packing of things for future shipping and distribution. (McWhorter, 2017)

    Serial Commas in Referencing Guides

    It is a common misconception that referencing guides need to be followed to the point of including American punctuation (e.g. using the serial comma and double quotation marks) and date formats, even when British/Australian English has been used in the document.

    Guides such as APA and Chicago use American punctuation because they were originally created by American institutions for an American audience. When Australian institutions have adopted them, many of them have failed to correctly alter their guides to reflect the correct use of British/Australian English.

    If British/Australian English has been applied to the document, it should be applied to the referencing style also. This means undergraduate and postgraduate students at Australian and New Zealand universities shouldn’t be using the serial comma in their referencing.

    The serial, Oxford, and Harvard comma

    The serial, Oxford, and Harvard comma
    The serial comma (also known as the Oxford comma and the Harvard comma) is the comma used immediately before a grammatical conjunction (usually and, or, and sometimes nor) preceding the final item in a list of three or more items. For example, this three-country list can be punctuated as either Portugal, Spain, and France (with the serial comma) or as Portugal, Spain and France (without the serial comma). To separate words, phrases, or clauses of a series of 3 or more elements, include a comma before the closing and or or. Routine use of the serial comma helps to prevent ambiguity. Graphic Design is all about clear communication and the serial comma helps clarify content. Good designers and copywriters use the serial comma.
    The Harvard, Oxford, or serial comma:
         • better matches the spoken cadence of sentences
         • often reduces ambiguity
         • matches practice with other means of separating items in a list (example: when semicolons are used to separate items, a semicolon is consistently included before the last item, even when 'and' or 'or' is present)
    The Chicago Manual of Style, Strunk and White's Elements of Style, most authorities on American English and Canadian English, and some authorities on British English recommend the use of the serial comma. Most US college writing handbooks advocate use of the serial comma.
    Some newspaper style guides recommend not using the serial comma, possibly for economy of space. In the narrow width of a newspaper column this saving counts for more than elsewhere. But here or anywhere one must question whether the advantage outweighs the confusion caused by the omission. Writers use the comma between all members of a series, including the last two, on the common-sense ground that to do so will minimize ambiguities and annoyances at a negligible cost.

    The guests included two strippers, John Kennedy, and Joseph Stalin.
    The guests included two strippers, John Kennedy and Joseph Stalin.
    A book dedication quoted by Teresa Hayden:     To my parents, Ayn Rand and God.
    There is ambiguity about the writer's parentage – the reader could believe that the writer refers to Ayn Rand and God as her parents. A comma before the and removes the ambiguity:      To my parents, Ayn Rand, and God.
    Here are some types of sandwiches: pastrami, ham, cream cheese and peanut butter and jelly.
    According to the two most plausible interpretations of this sentence, four kinds of sandwich are listed. But it is uncertain which are the third and fourth kinds – cream cheese and peanut butter or peanut butter and jelly. Adding a serial comma removes this ambiguity. With a comma after peanut butter, the kinds of sandwich are these:
         • Pastrami
         • Ham
         • Cream cheese and peanut butter
         • Jelly
    With a comma after cream cheese, the kinds of sandwich are these:
         • Pastrami
         • Ham
         • Cream cheese
         • Peanut butter and jelly
    Other examples:
         • red, white, and blue
         • horses, mules, and cattle
         • height, width, and depth
         • by the bolt, by the yard, or in remnants
         • a, b, and c
         • neither snow, rain, nor sleet
         • I want no ifs, ands, or buts
         • The meal consisted of soup, salad, and macaroni and cheese
    The bottom line
    • Omitting the final comma may cause ambiguity or confusion.
    • Including the final comma will almost never cause ambiguity or confusion.
    • Consistency is key. If you're going to use the serial comma once, then use it every time. The serial comma is necessary in some cases, and consistency then requires it be used in other cases.

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