See C1 in the Quick Editing Guide for more on comma usage.
Like a split-second pause in conversation, a well-placed comma helps your readers to catch your train of thought. It keeps them from stumbling over a solid block of words or drawing an inaccurate conclusion.
Lyman paints fences and bowls.
From this statement, we can deduce that Lyman is a painter who works with both a large and a small brush. But add commas and the portrait changes:
Lyman paints, fences, and bowls.
Now Lyman wields a paintbrush, a sword, and a bowling ball. What we learn about his activities depends on how the writer punctuates the sentence.
| 21a | Use a comma with a coordinating conjunction to join two main clauses |
main clause: A group of words that has both a subject and a verb and can stand alone as a complete sentence: My friends play softball.
phrase: Two or more related words that work together but may lack a subject (as in will walk), a verb (my uncle), or both (to the attic)
When you join main clauses with a coordinating conjunction (and, but, for, or, nor, so, yet), add a comma after the first clause, right before the conjunction.
The pie whooshed through the air, but the agile Hal ducked.
If your clauses are short and parallel in form, you may omit the comma. Or you may keep the comma to throw emphasis on your second clause.
| Spring passed and summer came. | Spring passed, and summer came. |
| They urged but I refused. | They urged, but I refused. |
CAUTION: Don’t use a comma with a coordinating conjunction that links two phrases or that links a phrase and a clause.
| FAULTY | The mustangs galloped, and cavorted across the plain. |
| EDITED | The mustangs galloped and cavorted across the plain. |
| 21b | Use a comma after an introductory clause, phrase, or word. |
clause: A group of related words that includes both a subject and a verb: The sailboats raced (independent clause) until the sun set (subordinate clause).
Weeping,Lydia stumbled down the stairs.
Before that, Arthur saw her reading an old love letter.
If he knew who the writer was, he didn’t tell.
Placed after any such opening word, phrase, or subordinate clause, a comma tells your reader, “Enough preliminaries: now the main clause starts.”
EXCEPTION: You need not use a comma after a single introductory word or a short phrase or clause if there is no danger of misreading.
Sooner or later Lydia will tell us the whole story.
| 21c | Use a comma between items in a series. |
When you list three or more items, whether they are nouns, verbs, adjectives, adverbs, or entire phrases or clauses, separate them with commas.
Country ham, sweet corn, and potatoes weighted Grandma’s table.
Joel prefers music that shakes, rattles, and rolls.
In one afternoon, we climbed the Matterhorn, voyaged beneath the sea, and flew on a rocket through space.
Notice that no comma follows the final item in the series.
NOTE: Some writers omit the comma before the final item in the series. This custom may throw off the rhythm of a sentence and, in some cases, obscure the writer’s meaning. Using the comma in such a case is never wrong and is preferred in academic style; omitting it can create confusion.
I was met at the station by my cousins, brother and sister.
Are these people a brother-and-sister pair who are the writer’s cousins? Or are they a group consisting of the writer’s cousins, her brother, and her sister? If they are more than two people, a comma would clear up the confusion.
I was met at the station by my cousins, brother, and sister.
| 21d | Use a comma between coordinate adjectives but not between cumulative adjectives. |
Adjectives that function independently of each other, though they modify the same noun, are called coordinate adjectives. Set them off with commas.
Ruth was a clear, vibrant, persuasive speaker.
Life is nasty, brutish, and short.
CAUTION: Don’t use a comma after the final adjective before a noun.
| FAULTY | My professor was a brilliant, caring, teacher. |
| EDITED | My professor was a brilliant, caring teacher. |
conjunction: A linking word that connects words or groups of words through coordination (and, but) or subordination (because, although, unless)
To check whether adjectives are coordinate, ask two questions. Can you rearrange the adjectives without distorting the meaning? (Ruth was a persuasive, vibrant, clear speaker.) Can you insert and between them? (Life is nasty and brutish and short.) If the answer to both is yes, the adjectives are coordinate. Removing any one of them would not greatly affect the others. Use commas between them to show that they are separate and equal.
NOTE: If you link coordinate adjectives with and or another conjunction, omit the commas except in a series (see 21c).
New York City is huge and dirty and beautiful.
Cumulative adjectives work together to create a single unified picture of the noun they modify. No commas separate them.
Ruth has two small white poodles.
Who’s afraid of the big bad wolf?
See more on cumulative adjectives.
If you remove, rearrange, or insert and between cumulative adjectives, the effect is distorted (two white small poodles; the big and bad wolf ).
| 21e | Use commas to set off a nonrestrictive phrase or clause. |
modifier: A word (such as an adjective or adverb), phrase, or clause that provides more information about other parts of a sentence: Plays staged by the drama class are always successful.
A nonrestrictive modifier adds a fact that, while perhaps interesting and valuable, isn’t essential. You could leave it out of the sentence and still make sense. Set off the modifier with commas before and after.
Potts Alley, which runs north from Chestnut Street, is too narrow for cars.
At the end of the alley, where the fair was held last May, a getaway car waited.
A restrictive modifier is essential. Omit it and you significantly change the meaning of the modified word and the sentence. Such a modifier is called restrictive because it limits what it modifies: it specifies this place, person, or action and no other. Because a restrictive modifier is part of the identity of whatever it modifies, no commas set it off from the rest of the sentence.
They picked the alley that runs north from Chestnut Street because it is close to the highway.
Anyone who robs my house will be disappointed.
Leaving out the modifier in that last sentence changes the meaning from potential robbers to humankind.
NOTE: Use that to introduce (or to recognize) a restrictive phrase or clause. Use which to introduce (or to recognize) a nonrestrictive phrase or clause.
The food that I love best is chocolate.
Chocolate, which I love, is not on my diet.
| 21f | Use commas to set off nonrestrictive appositives. |
appositive: A word or group of words that adds information by identifying a subject or object in a different way: my dog Rover, Hal’s brother Fred
Like the modifiers discussed in 21e, an appositive can be either restrictive or nonrestrictive. If it is nonrestrictive — if the sentence still makes sense when it is omitted or changed — then set it off with commas before and after.
My third ex-husband, Hugo, will be glad to meet you.
We are bringing dessert, a blueberry pie, to follow dinner.
If the appositive is restrictive — if you can’t take it out or change it without changing your meaning — then include it without commas.
Of all the men I’ve been married to, my ex-husband Hugo is the best cook.
| 21g | Use commas to set off conjunctive adverbs. |
conjunctive adverb: A linking word that can connect independent clauses and show a relationship between two ideas: Jen studied hard; finally, she passed the exam. (See 14a–14c.)
parenthetical expression: An aside to readers or a transitional expression such as for example or in contrast
When you drop a conjunctive adverb into the middle of a clause, set it off with commas before and after.
Using lead paint in homes has been illegal, however, since 1973.
Builders, indeed, gave it up some twenty years earlier.
| 21h | Use commas to set off parenthetical expressions. |
Use a pair of commas around any parenthetical expression or any aside from you to your readers.
Home inspectors, for this reason, sometimes test for lead paint.
Cosmic Construction never used lead paint, or so their spokesperson says, even when it was legal.
| 21i | Use commas to set off a phrase or clause expressing contrast. |
It was Rudolph, not Dasher, who had a red nose.
EXCEPTION: Short contrasting phrases beginning with but need no commas.
It was not Dasher but Rudolph who had a red nose.
| 21j | Use commas to set off an absolute phrase. |
absolute phrase: An expression, usually a noun followed by a participle, that modifies an entire clause or sentence and can appear anywhere in the sentence: The stallion pawed the ground, chestnut mane and tail swirling in the wind.
The link between an absolute phrase and the rest of the sentence is a comma or two commas if the phrase falls in midsentence.
Our worst fears drawing us together, we huddled over the letter.
Luke, his knife being the sharpest, slit the envelope.
| 21k | Use commas to set off a direct quotation from your own words |
See 25g–25i for advice on using punctuation marks with quotations; see 25a–25d and C3 in the Quick Editing Guide for advice on using quotation marks.
When you briefly quote someone, distinguish the source’s words from yours with commas (and, of course, quotation marks). When you insert an explanation into a quotation (such as he said), set that off with commas.
Shakespeare wrote, “Some are born great, some achieve greatness, and some have greatness thrust upon them.”
“The best thing that can come with success,” commented the actress Liv Ullmann, “is the knowledge that it is nothing to long for.”
The comma always comes before the quotation marks.
EXCEPTION: Do not use a comma with a very short quotation or one introduced by that.
linking verb: A verb (is, become, seem, feel) that shows a state of being by linking the sentence subject with a word that renames or describes the subject: The sky is blue. (See 3a.)
Don’t tell me “yes” if you mean “maybe.”
Jules said that “Nothing ventured, nothing gained” is his motto.
Don’t use a comma with any quotation run into your own sentence and read as part of it. Often such quotations are introduced by linking verbs.
Her favorite statement at age three was “I can do it myself.”
Shakespeare originated the expression “my salad days, when I was green in judgment.”
| 21l | Use commas around yes and no, mild interjections, tag questions, and the name or title of someone directly addressed |
interjection: A word or expression (oh, alas) that inserts an outburst of feeling at the beginning, middle, or end of a sentence
| YES AND NO | Yes, I’d like a Rolls-Royce, but, no, I didn’t order one. |
| INTERJECTION | Well, don’t blame it on me. |
| TAG QUESTION | It would be fun to ride in a Silver Cloud, wouldn’t it? |
| DIRECT ADDRESS | Drive us home, James. |
| 21m | Use commas to set off dates, states, countries, and addressess |
On June 6, 1995, Ned Shaw was born.
East Rutherford, New Jersey, seemed like Paris, France, to him.
His family moved to 11 Maple Street, Middletown, Ohio.
Do not add a comma between state and zip code: Bedford, MA 01730.
| 21n | Do not use a comma to separate a subject from its verb or a verb from its object |
| FAULTY | The athlete driving the purple Jaguar, was Jim Fuld. [Subject separated from verb] |
| EDITED | The athlete driving the purple Jaguar was Jim Fuld. |
| FAULTY | The governor should not have given his campaign manager, such a prestigious appointment. [Verb separated from direct object] |
| EDITED | The governor should not have given his campaign manager such a prestigious appointment. |
| 21o | Do not use a comma between words or phrases joined by correlative or coordinating conjunctionss |
See lists of coordinating words.
Do not divide a compound subject or predicate unnecessarily with a comma.
| FAULTY | Neither Peter Pan, nor the fairy Tinkerbell, saw the pirates sneaking toward their hideout. [Compound subject] |
| EDITED | Neither Peter Pan nor the fairy Tinkerbell saw the pirates sneaking toward their hideout. |
| FAULTY | The chickens clucked, and pecked, and flapped their wings. [Compound predicate] |
| EDITED | The chickens clucked and pecked and flapped their wings. |
| 21p | Do not use a comma before the first or after the last item in a series. |
| FAULTY | We had to see, my mother’s doctor, my father’s lawyer, and my dog’s veterinarian, in one afternoon. |
| EDITED | We had to see my mother’s doctor, my father’s lawyer, and my dog’s veterinarian in one afternoon. |
| 21q | Do not use a comma to set off a restrictive word, phrase, or clause |
For an explanation of restrictive modifiers, see 21e.
A restrictive modifier is essential to the definition or identification of whatever it modifies; a nonrestrictive modifier is not.
| FAULTY | The fireworks, that I saw on Sunday, were the best I’ve ever seen. |
| EDITED | The fireworks that I saw on Sunday were the best I’ve ever seen. |
| 21r | Do not use commas to set off indirect quotations |
For more on quoting someone’s exact words, see 25a–25c.
When that introduces a quotation, the quotation is indirect and requires neither a comma nor quotation marks.
| FAULTY | He told us that, we shouldn’t have done it. |
| EDITED | He told us that we shouldn’t have done it. |
This sentence also could be recast as a direct quotation.
| EDITED | He told us, “You shouldn’t have done it.” |