Serial or Oxford Comma: When Is It Used?

Summary

The serial comma is used before the conjunction (and, or) that marks the final item in a series. It is placed after the second-last item in a list.

Example
  • We had cats, dogs, and horses on the farm.

Using the serial comma is optional, except when not using it would result in confusion.

Examples
  • Incorrect: My favorite people are my sisters, Lady Gaga and Beyoncé.
    Unless your sisters are the two famous singers, use a serial comma.
  • Correct: My favorite people are my sisters, Lady Gaga, and Beyoncé.

Don’t use a serial comma when a pair of words or phrases are used descriptively rather than in a series.

Example
  • Meet my two best friends, Rita and Anita.
    The best friends are Rita and Anita, so there’s no comma before and.

The serial comma is seen more often in American than in British usage. Its use is also more common in academic than in creative writing and news copy.

What is the serial or Oxford comma?

The serial comma, also called the Oxford comma or Harvard comma, is the comma before the concluding conjunction (and, or) in a series. It appears after the second-last item in a list of three or more items in a sentence.

Examples
  • Maya’s favorite colors are green, blue, and black.
    The serial comma is the one before and.
  • We visited Thailand, Indonesia, Vietnam, and Malaysia last year.
  • Use pens, pencils, or crayons for this project.

The serial comma is used right before the conjunction (and, or) that precedes the final item in a series. Although not grammatically necessary, the use of this comma is preferred in academic and other formal writing, especially in American usage.

When to use

A serial comma can be essential to the meaning of a sentence. Always use the serial comma if not using it would result in ambiguity or confusion.

Example
  • Confusing: My idols are my parents, Neil Armstrong and Kamala Harris.
    Without a comma before and, this sentence could mean that my parents are Neil Armstrong and Kamala Harris.
    Clearer: My idols are my parents, Neil Armstrong, and Kamala Harris.
Caution

Be careful to place the comma correctly. It doesn’t always go before the final and.

Examples
  • Poco ordered milk, toast, and eggs and bread.
    The final item is “eggs and bread,” so the comma goes before it.
  • I’ll have the muffin, the cupcake, and the ice-cream and brownie.
  • On the menu are broccoli, peas, and steak and potatoes.

But most often, the serial comma isn’t essential to meaning. Then, whether to use it or not depends on the style you follow. Remember that the serial comma appears after the penultimate element in a series and is followed by a conjunction like and or or. The series you’re punctuating could comprise words, phrases, or clauses.

Examples
  • May you find health, wealth, and happiness.
  • Would you like tea, coffee, or orange juice?
  • We tested the vaccine on young, middle-aged, and older adults.
  • You will need fresh broccoli, powdered ginger, and grated cheese.
  • Profits have sunk, jobs are gone, and salaries have been slashed at thousands of businesses this year.
  • The dog lay on the couch, the cat sat on the chair, and the human made do with a futon.

Differences in American and British usage

The serial comma is often used in American English, especially in formal writing. In British writing, it is generally omitted.

Examples
  • American: A vision board is a collage of clippings, pictures, fabric, memos, quotes, notes, and more as a way of visualizing one’s future goals.
    — “Words We’re Watching: Vision Board,” Merriam Webster’s “Words We’re Watching”
  • American: We also heard from psychologists who write about religion, classical literature, and ancient philosophy as an essential part of their work.
    — “Citing classical and religious works,” APA Style Blog
  • British: Today, we’re looking at idioms containing a wider range of weather – sun, rain and clouds.
    — “Every Cloud Has a Silver Lining,” About Words (A Blog from Cambridge Dictionary)
  • British: Less than a century later, Oxford had achieved eminence above every other seat of learning in the country, and had won the praises of popes, kings and sages by virtue of its antiquity, curriculum, doctrine and privileges.
    — “Introduction and History,” Website of the University of Oxford
Caution

Even if you follow a style that doesn’t require a serial comma, you must still use it if doing so is necessary to the meaning of the sentence.

Example
  • Meaning 1: I live with my friends, my cat and my dog.
    Your friends are your cat and your dog, and you live with them.
    Meaning 2: I live with my friends, my cat, and my dog.
    You live with your friends and with your cat and your dog.

Differences in academic, creative, and news writing

In academic, business, and other formal writing, where it is important to convey exact meaning, the serial comma is generally preferred, especially in American usage.

Examples
  • We stratified the priority list into three tiers (critical, high, and medium priority).
    — from an article in Lancet
  • Consequently, bacteria play a major role in bodily functions, including immunity, digestion, and protection against disease.
    — from an article in Clinical Microbiology Reviews
  • Evolutionarily conserved elements in vertebrate, insect, worm, and yeast genomes
    — title of a paper published in Genome Research
  • A highly soft, stretchable, and sticky polydimethylsiloxane‐based elastomer is achieved by adding small fractions of an amine‐based polymer.
    — from an article in Advanced Materials

In creative writing, where rhythm and cadence are more important than consistency and unambiguity, the serial comma is often omitted (though some writers may prefer it, and that is perfectly fine).

Examples
  • There was silence, pressure and utter, utter darkness.
    Terry Pratchett, Hogfather (1996)
  • She represents love, beauty, purity, the ideal female and the moon . . . and she’s the mystère of jealousy, vengeance and discord, and, on the other hand, of love, perpetual help, goodwill, health, beauty and fortune.
    Zadie Smith, On Beauty (2005)

But even in creative writing, you’ll notice a difference between British and American usage: the serial comma appears more frequently in American than in British writing.

Examples
  • ‘Death is horrible, final, and frequently premature,’ Coach Bob declared.
    John Irving, The Hotel New Hampshire (1981)
  • That’s what a family is. Also the storm at sea, the ship, and the unknown shore.
    Michael Chabon, The Yiddish Policemen’s Union (2007)

Finally, in news copy, the serial comma is generally omitted.

Examples
  • Every Friday, be the first to see reviews, news and features in The New York Times Book Review.
  • The rucksack didn’t contain any significant clues: just some bread, a bottle of Fanta, a bottle of water and a pair of trainers.
    — “Out of Thin Air: The Mystery of the Man Who Fell from the Sky,” The Guardian (April 15, 2021)
  • After calls by the AP in the key states of Arizona, Michigan and Wisconsin, Biden holds an Electoral College advantage of 264 votes to Trump’s 214.
    — “Where Presidential Election Votes Are Still Being Counted,” NPR (November 5, 2020)

AP style

The AP Stylebook, followed in U.S. journalism, recommends against the general use of the serial comma.

Examples
  • We asked those who teach music, history and philosophy.
  • Results are expected today from Iowa, Ohio and Georgia.

In a complex series of phrases or clauses, however, it does suggest using the serial comma to make ideas clearer to the reader.

Example
  • We need to check who the stakeholders are, whether they have been consulted, and what their requirements are.

Finally, like all style guides, the AP Stylebook recommends placing a serial comma before the closing conjunction in a series whenever not using one would cause confusion.

Examples
  • Poor: The committee consulted the staff, counsellor Ellen Hardy and psychologist Petra Rostov.
    Without a serial comma, it reads as though the staff are the counsellor and the psychologist.
  • Better: The committee consulted the staff, counsellor Ellen Hardy, and psychologist Petra Rostov.
    Makes it clear that there are three elements in this series: (1) the staff, (2) a counsellor, (3) a psychologist.

Chicago, APA, and MLA style

Most style guides used in academic writing, including the Chicago Manual of Style, APA Publication Manual, and MLA Handbook, prescribe using the serial comma.

Examples
  • We asked those who teach music, history, and philosophy.
  • Results are expected today from Iowa, Ohio, and Georgia.
  • We must ask whether this policy is truly necessary, whether lesser measures could suffice, and whether such a change in law requires a referendum.

Thus, whether to use a serial comma can depend on the style guide followed by your academic program, journal, or publisher.

When not to use

Don’t use the serial comma if, instead of presenting a list, you are simply providing additional information or describing something (i.e., using a nonessential appositive).

Examples
  • I grew up with my brothers, Marc and Antony.
    My brothers are Marc and Antony.
  • Over us loomed a shadow, deep and dark.
  • Her parents, Jen and Jon, are our friends.
Caution

Remember that the serial comma can affect the meaning of a sentence. Spell-check will often steer you wrong when it comes to commas with appositives, so this is something you should check for yourself.

Also, be careful to place the serial comma correctly in a series in which the final item is a pair of words or phrases joined by and.

Examples
  • In the cabin, we found all the old favorites: ludo, checkers, and snakes and ladders.
  • I miss my room, my bed, and my mom and dad.

Serial semicolon

Semicolons instead of commas are used to punctuate lists where the individual elements themselves contain internal commas. If the style you follow requires serial commas, use serial semicolons instead in a complex series.

Examples
  • Votes are still being counted in Atlanta, Georgia; Dallas, Texas; and Raleigh, North Carolina.
  • Here is a list of our favorite cafes in Koh Samui, Thailand; Bali, Indonesia; and Langkawi, Malaysia.

Quick Quiz

Which of these contains a serial comma?
Choose from these answers
All done!
Which of these is punctuated correctly?
Choose from these answers
All done!
Which of these means that your parents are famous singers?
Choose from these answers
All done!
Which of these means your parents are a doctor and a teacher?
Choose from these answers
All done!

Did You Know?

Any can be used with both count and mass nouns (any of the students, any of the water).
Know more:Any Is or Are: Is Any Singular or Plural?