Advanced Comma Rules

There are many rules governing punctuation, but using appropriate punctuation isn't about following rules just for the sake of it. Rather, the rules for using punctuation act as a shared set of expectations between writers and readers. As a reader, you look to punctuation for signals about what the author intended to say. In your own writing, you will want to use punctuation appropriately to express your ideas as clearly as possible. In this way, punctuation is a tool that helps you inform, persuade, or entertain your audience. 

Read this information about comma rules and complete the practice activities. When you finish, check your answers against the Answer Key.

The comma is an important organizational tool for the writer that ultimately helps the reader. Without commas, a reader would often have to go back and reread a sentence to understand what the writer meant. Of course, there are rules for when to use a comma and when it is not necessary to use one. Instead of sprinkling commas throughout your papers, use a comma only when you know of a good reason to use one – when you know a rule for its use. 

There are only seven comma rules you need to know in order to master the comma and make your writing easier to read. Some of these rules have already been discussed in Fragments, Comma Splices, and Run-Ons, but other uses will be new; be sure to go through the entire lesson.


Comma Rule 1: Put a comma BEFORE and, but, for, or, nor, yet, and so when they connect two independent clauses.

(Reminder: An Independent Clause has the same three qualities as a sentence: a main verb, a subject, and the expression of a complete thought. In fact, a sentence is an independent clause.)

The dog ate Tom's homeworkso he asked his teacher for an extension.

Be sure those words do connect two independent clauses. The following sentence is only one independent clause with one subject and two verbs; therefore, no comma is needed.

Tom needed more time for his paper and asked for an extension.


Comma Rule 2: Put a comma between items in a series:

Harvey ordered a milkshake, a piece of pie, a brownie, and a soda.

Diana picked up the phone, dialed Harvey's number, and asked how he was feeling.

Some words seem to go together and don't need a comma between them, even though they make up a series:

Large bright shiny stones bordered the path to the beach.

(Not "Large, bright, shiny."..)

The stones were placed there by the little old lady.

(Not "Little, old."..)

One way to determine whether or not a comma is needed between two words in a series is to see if the word and can be used naturally between them. For example, it wouldn't sound right to say, "A little and old lady...". Simply put a comma where an and would sound right.

There is one more part to the series rule: If an address or date is used in a sentence, treat it as a series:

Joanna was born on February 4th, 1983, in Albuquerque, New Mexico, and lived there until August 20th, 2000, when she moved to Santa Cruz, California, to attend Cabrillo College.


Comma Rule 3: Put a comma after an introductory word, phrase, or dependent clause that doesn't flow smoothly into the sentence or before an afterthought that is added at the end of the sentence.

(Reminder: A Dependent Clause has a subject and a verb, but it doesn't express a complete thought. It depends on an independent clause to give it meaning. For example, "If you decide not to attend…" is an incomplete thought.)

Well, I'm glad my mid-term exams are over and done with.

When I got to school, all the parking lots were full.

It's nearly time for classisn't it?


Comma Rule 4: Put commas around the name of a person being spoken to.

I hopeAlexander, that you'll be able to give me a ride.

Angelica, I'll be happy to if my car starts.

You should know that I don't like dentistsDr. Paine.


Comma Rule 5: Put commas around interrupters – expressions that interrupt the flow of the sentence (such as finally, of course, by the way, on the other hand, Ithink, etc.).

You knowof course, it's a long way to drive.

The whole tripI think, will take about twelve hours.

She decidedfinally, to stay home.

Note: When a word such as however, moreover, therefore, furthermore, etc. comes between two independent clauses, that word always has a semicolon before it. Semicolons and colons were discussed in another section.


Comma Rule 6: Put commas around defining or amplifying material – material that, if left out, will not affect the sense or main idea of the sentence.

Felipewhose sister used to date my cousin, has decided to go to medical school.

The new parking lotswhich took several months to build, will be ready next week.

His black bootsthe ones he bought in San Francisco, make him look much taller.


Comma Rule 7: Use a comma in between speech in quotation marks and the rest of the sentence.

"Sorry that I'm late", he said.

She replied, "Don't worry, I wasn't on time either".


Practice 1: Punctuate the following sentences using the first three comma rules:

  1. When the large earthquake shook Seattle Phillip decided to move back to New York.
  2. No I'm not ready to make a serious commitment.
  3. Jaime is majoring in Elementary Education isn't that right?
  4. In Robin's opinion baseball is ten minutes of excitement packed into three hours.
  5. In the college cafeteria one can hear students speaking Spanish Japanese Italian Arabic Russian Portuguese Farsi and many other languages.
  6. Lars has been studying Chinese for more than ten years but he's never had the opportunity to visit China.
  7. When I entered the house was in darkness.
  8. Her brother insisted that she be on time yet when she arrived he wasn't there.
  9. To be perfectly frank students need to know the fundamentals of grammar before they can write acceptable college papers.


Practice 2: Punctuate the following sentences using the last four comma rules:

  1. College students of course need the fundamentals of grammar.
  2. Grammar which can be rather tedious does not make a person a good writer by itself.
  3. What is necessary experts agree is for students to write more in all of their classes.
  4. "One doesn't know anything clearly" S.I. Hayakawa said "unless one can state it in writing".
  5. Yes William you will have to do a lot of writing in law school.
  6. Every profession I think requires some sort of writing at some time.

Source: Washington State Board for Community and Technical Colleges,
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Last modified: Friday, January 8, 2021, 1:25 PM