Commas

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Commas in a Series

In a series, commas separate the different items. Generally, a conjunction (and, or) will follow the last comma in the list. Although the serial—or Oxford comma (the comma preceding and in a series)—is not used in journalistic writing, it is still used in formal and academic writing.

Example:     I went to the concert with Amy, Dave, June, and Isaac.

Note:  the use of an ampersand (&) instead of and in a series does not require a serial comma.

Example:     I received counsel from Brooks, McCarthy, Dunn & Derringer, Attorneys at Law.

Note: commas are not needed in a series whose elements are all joined by conjunctions.

Examples:   I went with Amy and Dave and Isaac.
Was it fun or boring or what?

Etc. and so forth are both preceded and followed by a comma.

Examples:   I went with Isaac, June, etc., to the concert.
The bagger asked me if I wanted paper, plastic, and so forth, after I had paid the cashier.

Introductory Phrases

Introductory phrases are adverbials or participle phrases at the beginning of sentences that explain when, where, why, how, or under what circumstances the action of the sentence occurs.

Example:     When Jane turns twenty-one, she will buy a new car.
Putting the pedal to the metal, he ran the red light.

A comma follows a conjunctive adverb when it begins a sentence.

Example:     Accordingly, Sue put on her hat and coat.
Nevertheless, Kafka portrays artists as cast-out loners.

Note: For a list of conjunctive adverbs see the handout Comma Splices and Fused Sentences.

Use commas after and around mild exclamations or other interjections at the beginning of a sentence.

Example:     Oh, I hope we're not late.

Don’t use a comma if the introductory phrase immediately precedes the verb it modifies.

Example:     Out of the pool stepped the bathing beauty.
Running beside the car was Jerry’s mother.

Note: It is never wrong to use a comma after a short introductory phrase of less than four words, but if the comma does not add clarity to the sentence, you can leave it out.

No comma needed:   On Tuesday he went bowling.
Comma needed:        With Howard, Dean went bowling.

Independent Clauses

Independent clauses are groups of words that can be a sentence on their own. When two independent clauses are combined using a conjunction, a comma must precede the conjunction (and, or, but, etc.).

Example:     Molly likes to read books, but she won't visit the library alone.

Compound predicates

A comma is not used with a compound predicate. A compound predicate is a structure where two clauses share the same subject.

Example:     Molly likes to read but won’t visit the library alone.

In the example above, Molly serves as the subject for likes to read as well as won’t visit the library alone; therefore, it is a compound predicate, and no comma is needed after the conjunction but. (For more information on commas in independent clauses see the handout Comma Splices and Fused Sentences.)

Restrictive vs. Nonrestrictive modifiers

A restrictive modifier is word or phrase that modifies a noun and is essential to the meaning of the sentence. There are no commas around restrictive modifiers.

Example:     The movie starring Tom Cruise was very action packed.

In this case, the speaker is specifying one movie out of many movies that he or she has watched—the one with Tom Cruise.

A nonrestrictive modifier is information that is not essential to the meaning of the sentence, requiring a pair of commas to set it off from the surrounding text. In this way the commas act like parentheses.

Example:     Minority Report, starring Tom Cruise, was very action packed.

Starring Tom Cruise is a nonrestrictive modifier because it is non-essential to the meaning of the sentence.

Commas with two or more adjectives

When a noun is preceded by two or more adjectives, use commas to separate the adjectives from one another. Don’t use a comma between the adjective and the noun it describes.

Examples:   Darth Vader is a chilling, extreme example of the power of evil.
We watched the colorful, peaceful, gorgeous sunset.

Introducing quotes

Quotations are usually introduced with a comma.

Example:     In a 1995 study, Dr. James Brienholt states, “The correlation between obesity and the rising number of fast-food restaurants cannot be ignored.”

Do not use a comma if the quoted material is grammatically part of the sentence.

Incorrect:    Dr. Brienhlot suggests that, “obesity and fast food will be forever linked.”
Correct:       Dr. Brienholt suggests that “obesity and fast food will be forever linked.”

Dates and places

In the month-day-year style of writing dates, always place a comma after the day and before the year.

Example:     March 15, 1978

When stating place names, use a comma to separate the city/state from the state/country.

Examples:   Paris, France
Springfield, Illinois

Elliptical constructions

A comma can be used to indicate the omission of a word where the meaning can be understood easily.

Example:     Danny won five games; Mark, seven.

Here the comma is used to indicate the omission of won between Mark and seven.

James Gunter, spring 2005
Based on a handout by Cecily Young, Aug. 1999