The English Department's
Quick Guide to Using Commas

Use a comma before a coordinating conjunction (and, but, for, nor, or, so, yet) that links independent clauses (a subject and a predicate).

• I wanted to take the Concorde to Paris, but I didn’t have enough money.
• Mr. Jones has been the head of this department for 20 years, and he’s still got another 20 left in him.
• Sharon would not do windows, nor would she wash floors.
• I was excited about my new job, yet I was also nervous.

• Should I stay or should I go?
• He went to the store and he bought some milk.

• Wrong: George really wanted that new car so, he started saving for the down payment.
• Right: George really wanted that new car, so he started saving for the down payment.

• Wrong: I want to get more exercise but, I'm too lazy.
• Right: I want to get more exercise, but I'm too lazy.

Use a comma to set off introductory words, phrases, and clauses from the main part of the sentence.

Set off each introductory interjection, transition, Yes, or No.

• Interjection: Well, I’m glad you got here safely.
• Interjection: Gee, that hurt my feelings.
• Transition: Furthermore, the committee recommends a pay raise for all employees.
• Transition: Likewise, we think everyone should have Fridays off.
• Transition: By the way, I’ll be late for dinner tonight.
• Yes/No: Yes, the store will be open on Labor Day. No, it will not be open on Christmas.

Set off opening adverb clauses from the main clause.

• When you use commas correctly, your writing looks more professional.
• After a long day at work, Martina likes to unwind with a good book.

Use commas to separate items in a series. These are called serial commas.

Note: Some style guides and grammar checkers don't recommend serial commas, but I feel they avoid confusion by keeping list items clearly separate.

• Billy packed his pajamas, his toothbrush, and his comic books.
• Sara’s makeup bag contained mascara, eye shadow, foundation, powder, eyeliner, and two lipsticks.
• Stop, look, and listen.
• They walked down the block, turned left, passed the old Post Office, and then turned right to get to the beach.

Exception: If the items in a series already contain commas, use semicolons to separate these items.

• People had come to the seminar from Dallas, Texas; Atlanta, Georgia; Birmingham, Alabama; and even London, England.
• On the day of the picnic, Tom brought fried chicken, cole slaw, and potato salad; Jill brought cheese, crackers, and bread; and Lynne brought ice cream, a pie, and some cookies.

Use a comma between adjectives that are not linked by a coordinating conjunction.

• It was a hot, humid, sultry day.
• I think you will like our new, improved product.
• Her dull, greasy hair fell into her smudged, dirty face.

Use a comma to set of parenthetical ideas or asides.

• Luke, who was never even late, missed the meeting entirely.
• Geoffrey Chaucer, the famous medieval poet, was also a government employee.
• The Norse god of thunder, Thor, drove a chariot pulled by two goats.
• Let us conclude, then, that it is better to be rich than to be poor.
• Search out your happiness, however long it may take you.

Use a comma to set off a thought that contrasts with the main clause.

• Nate, unlike Luke, is almost never on time.
• He really wanted to learn the material, not just get a good grade.
• The farmer kept ducks, not geese or chickens.
• Always put a comma before a coordinating conjunction, not after it.

Use a comma to separate items in dates and addresses.

• July 4, 1776, was an important date in American history.
• Your paper is due on Thursday, October 2, 1997.
• Our branch office is conveniently located on Main Street in Springfield, Massachusetts.
• The postmark on the letter said Brisbane, Australia.

General Guideline: If you’re unsure about comma placement, try reading your sentence out loud.

Put a comma where you’d pause if speaking. Then go back over this guide and see if any of the guidelines apply. Sometimes a comma simply helps the reader navigate a sentence or marks out units of meaning.

For example, compare the following pairs of sentences. See how a comma changes the meaning?

• I called Antonia my mother.
• I called Antonia, my mother.

• Still waters run deep.
• Still, waters run deep.

• Quiet people are trying to read.
• Quiet, people are trying to read.