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).
Exception: When both independent clauses are short, you may leave out the comma before and, but, or or.
- I wanted to take the Concorde to Paris, but I didnít have enough money.
- Mr. Jones has been the head of this department for 20 years, and heís 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.
Be careful: Always put the comma before the coordinating conjunction, not after it.
- 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, Iím 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, Iíll 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.
- Saraís 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 youíre unsure about comma placement, try reading your sentence out loud.
Put a comma where youíd 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.
© The English Department 1999