THE COMMA RULES
Commas do not have to be as tricky as we sometimes make them. In fact, if you can remember just six
rules, you will usually be correct. (Most of the time you will only be using the first four rules.) Along
with learning these rules, “listen” for pauses and, above all, do your best to make your writing as clear
as possible.
Please note that rules for using commas with quotation marks are not included in this document. These
rules will be covered as necessary in specific classes (e.g., creative writing) or for specific assignments
(e.g., research papers).
1.
2.
3.
4.
5.
6.
7.
USE A COMMA AFTER INTRODUCTORY ELEMENTS.
USE A COMMA BEFORE A CONJUNCTION THAT CONNECTS INDEPENDENT CLAUSES.
USE COMMAS TO SEPARATE ITEMS IN A SERIES.
USE TWO COMMAS TO SET OFF (OR ENCLOSE) EXPRESSIONS THAT INTERRUPT THE “MAIN” PART OF A SENTENCE.
USE A COMMA WHERE IT IS NECESSARY TO PREVENT MISREADING.
USE A COMMA BEFORE AN AFTERTHOUGHT OR CONTRASTING IDEA.
USE A COMMA BEFORE AND AFTER QUOTATION MARKS SURROUNDING DIRECT QUOTATIONS WITHIN A SENTENCE.
1. USE A COMMA AFTER INTRODUCTORY ELEMENTS.
A. INTRODUCTORY INTERJECTIONS AND SOME SHORT (nonessential) PHRASES:
Yes, please put your name on this paper.
In fact, putting your name on the paper is always a good idea.
Hey, did you forget already?
B. INTRODUCTORY CLAUSES: When we study grammar, we often get confused.
Once we get the hang of it, we love it!
C. LONG INTRODUCTORY PHRASES:
After many months of anticipation and excitement, we were thrilled to finally be in 10h grade.
Because of the brilliance of all our teachers, we feel smarter just walking down the hall.
EXCEPTION: You may omit the comma after short introductory phrases if they do not require a
pause and there is no possibility of misreading.
short intro. phrase
Throughout the summer we read, wrote, and practiced our math.
2. USE A COMMA BEFORE A CONJUNCTION THAT CONNECTS INDEPENDENT
CLAUSES
A. Be sure that the sentence has a coordinating conjunction: for, and, nor, but, or, yet, so (a.k.a.
“fanboys”). The most common are and, but, and or.
independent clause
I really like 11th grade,
independent clause
and I admire all my wonderful teachers.
independent clause
independent clause
I am looking forward to English class,
but I wish I didn’t have to get up so early.
B. Note that examples above have two independent clauses. In other words, the information on
both sides of the conjunction could stand as complete sentences. Compare that to the following
example, where no comma is needed because the words after the conjunction cannot stand
alone as a sentence.
independent clause
no verb; not a clause
I really like my school and all the wonderful teachers. (No comma needed)
EXCEPTION: Very short independent clauses are sometimes joined by the conjunction without
the comma. Be careful if you choose to use this exception to the rule.
We saw it and we liked it.
We walked but they ran to dinner.
3. USE COMMAS TO SEPARATE ITEMS IN A SERIES.
A. WORDS AND PHRASES: My favorite colors are red, white, and blue.
Don’t forget to study hard, read every night, and participate in class.
NOTE: DO put a comma before the conjunction. Although some writers omit this comma, MLA format
requires it. This comma is referred to as the “Oxford Comma.”
B. ADJECTIVES: You certainly are bright, energetic students.
The students loved their old, trusty, un-air-conditioned middle school.
NOTE: For the adjectives, put commas anywhere you could put the word “and.” DO NOT put a
comma between two adjectives when it would sound awkward to put “and” between them. Also,
do not place commas between adjectives that are commonly used together.
The students decided that they couldn’t think of any more interesting examples.
(There are THREE modifiers before the noun, but no commas are needed.)
We tried to clean the dusty old room.
(Do we need a comma between “dusty” and “old”? This is debatable, but
“dusty” and “old” are so commonly used together that the comma is probably
not mandatory.)
4. USE TWO COMMAS TO ENCLOSE (OR “SET OFF”) NON-ESSENTIAL INFORMATION
THAT INTERRUPTS THE NORMAL FLOW OF THE SENTENCE.
These interrupters go by a variety of terms, ranging from “nonessential” to “nonrestrictive” to
“parenthetical.” Regardless of the term, if the information is necessary to the meaning of the
sentence, it should NOT be set off by commas. If it is NOT essential, then it should be set off by
commas. Remember that commas tell your reader that the enclosed information is not as
important as the information in the rest of the sentence, so the reader’s voice will generally drop
when reading these elements.
There are six types of interrupters:
a. Appositives
b. Words in direct address
c. Parenthetical expressions
d. Subordinate adjective clauses
e. Participial Phrases
f. Dates and addresses
Appositives—but only when they are non-essential
Sally, my sister, is still at home.
Note that “my sister” is a non-essential or non-restrictive appositive, so it interrupts the
flow of the sentence. We DO enclose it (or set it off) with commas. Contrast that with
the following:
My brother Bob is leaving for college, but my brother Stephen is not.
Here, “Bob” and “Stephen” are essential to our understanding of the sentence. If we
removed them, the sentence would not make sense. Therefore, they are not interrupters;
rather, they are essential (a.k.a. “restrictive”) appositives, so we do NOT enclose them
with commas.
Words in Direct Address
Ladies and gentlemen, be sure to listen to all of the evidence presented.
The reason for homework, students, is to review concepts learned during the day.
Without your help, I would have had no idea how to attack that question, Sue.
Parenthetical Expressions
These expressions take on many grammatical forms and cannot be memorized. They can be clause,
phrases, or even individual words. In all cases they are not essential to the meaning of the sentence, so
they should be set off with commas. A good way to be sure that they are non-essential is to listen to
how your voice drops when you read them.
My brother, I am happy to announce, left for college yesterday.
My sister, on the other hand, was very sad to see him go.
I, however, was looking forward to having the laptop to myself.
Adjective Clauses—but only when they are non-essential
The freshmen, who were starting their first year in the high school, looked scared.
Students who were absent yesterday should get the notes from a friend.
Compare these two sentences. In the first, the clause is NON-ESSENTIAL, so it is set off by
commas. (All freshmen are starting their first year in high school.) In the second sentence,
the clause is ESSENTIAL to the meaning of the sentence, so it is not set off by commas.
(Only the students who were absent should get the notes.)
Participial Phrases—but only when they are non-essential
The new student, leaning forward to hear his classmate’s response, immediately participated in
the discussion.
Will the students sitting in the back row please move forward?
Apply the same thinking to participial phrases. In the first sentence, the reader knows which
student is being referenced, so the participial phrase describing the student’s behavior is
NON-essential. In the second sentence, the participial phrase limits or restricts the meaning
of the students, explaining which specific students should move forward. Since this
information is ESSENTIAL to the meaning of the sentence, no commas should be used.
Dates and Addresses
Though not necessarily interrupters or “non-essential,” dates and addresses are also enclosed with
commas. Note that ALL elements in the date or address should be enclosed (except for zip codes).
Pasadena, California, is the site of the Rose Bowl.
I applied for the job in July, 2014, and accepted it on August 26, 2014, A.D.
We recently moved to Doylestown, Bucks County, Pennsylvania 18901.
(No comma is needed before the zip code.)
RULES 5 AND 6 ARE LESS DEFINITIVE AND CAN BE TRICKY TO USE CORRECTLY. WHEN
DETERMINING IF A COMMA IS REQUIRED, APPLY RULES 1-4 IF POSSIBLE.
5. USE A COMMA WHERE IT IS NECESSARY TO PREVENT MISREADING.
CONFUSING: The day before I had seen him in a play.
CONFUSING: Those who can do.
MORE CLEAR: The day before, I had seen him in a play.
MORE CLEAR: Those who can, do.
6. USE A COMMA BEFORE AN AFTERTHOUGHT OR CONTRASTING IDEA.
Afterthought: For Canada, the War of 1812 was vitally important, far more important than it
was for Britain.
Contrasting Element: To understand a particular culture, we must consider the society as a
whole, not its individual parts. (Note that the first comma in this sentence is used because of
Rule #1. The second comma sets off the contrasting element.)