These three comma rules will solve more than 90% of your punctuation and sentence problems! Click here to download a free, printable copy of this handout.

Comma Rule 1

Use a comma when a sentence begins with an extra idea.

Because my grandmother has a swimming pool, I have always enjoyed swimming.

If an extra idea appears at the back of the sentence, do not use a comma:

I have always enjoyed swimming because my grandmother has a swimming pool. NO COMMA

Study these examples, noting which sentences have commas and which do not:

Although I enjoy swimming, I never learned how to water-ski.  COMMA

I never learned how to water-ski although I enjoy swimming. NO COMMA

When I approached the house, I saw an elderly man peering out the window.

I saw an elderly man peering out the window when I approached the house. NO COMMA

For your information, this parking lot is for physicians only.  COMMA

This handy rule covers subordinate clauses (word groups beginning with subordinate conjunctions such as if, when, because, although) as well as prepositional phrases (word groups beginning with prepositions such as of, in, by, for, with, to).

You can also state the rule this way: Use a comma any time a sentence begins with an introduction. It’s the same rule.

Comma Rule 2

Use a comma with a coordinate conjunction (a FANBOYS word) when there’s a sentence in front and in back.  And and but are the most important coordinate conjunctions.  Study these examples:

I enjoyed the movie, and I want to see it again.  COMMA

I enjoyed the movie and want to see it again. NO COMMA

The storm raged but didn’t spoil our fun.  NO COMMA

The storm raged, but it didn’t spoil our fun.  COMMA

FANBOYS words:  For And Nor But Or Yet So

Note:  These seven words are the only words you can use to join two sentences with a comma.

Comma Rule 3

Use two commas with an interrupter (a group of words with a voice change). Read these examples below, and notice that your voice drops when you come to the words in boldface. “Who” and “which” are typical interrupter words.

Bart Simpson, who often makes rude remarks to his parents, is not a good role model for children.

Superman, disguised as Clark Kent, fights a never-ending battle for the American way.

Other Tips

-Never use a comma directly after a subordinate or coordinate conjunction.  Study the examples above to see where commas are placed. It’s common (and wrong!) to see a comma placed after although. Don’t do it!

-The seven coordinate conjunctions (FANBOYS words) are the only words that can be used with a comma to join two sentences.  Use periods  with other words:

Bill washed his car. Then he waxed it.

The job I want pays well. Therefore, I expect a lot of competition.

I hoped to go to Europe this summer. However, I don’t have enough money.

If you want to get fancy, you can use a semicolon instead of a period. Remember that you never have to use a semicolon: A period is always correct.

Bill washed his car; then he waxed it.

The job I want pays well; therefore, I expect a lot of competition.

I hoped to go to Europe this summer; however, I don’t have enough money.

You can also view videos about Comma Rules 1 and 2 and Comma Rule 3. Listen to a podcast about commas by clicking here. Click here to download a free, printable copy of this handout.

© 2007 by Jean Reynolds