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. Be careful: Always put the comma before the coordinating conjunction, not after it.

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.

Set off opening adverb clauses from the main clause.

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.

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

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

Use a comma to set of parenthetical ideas or asides.

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

Use a comma to separate items in dates and addresses.

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?

© The English Department 1999