comma is a valuable, useful tool in a sentence because it helps the reader
pause in the right places. The rules provided here are those found in
traditional handbooks: however, in certain rhetorical contexts and for specific
purposes, these rules may be broken.
1. Use commas to separate independent
clauses when they are joined by any of these seven coordinating
AND, BUT, FOR, OR, NOR, SO, YET
The game was over (,) but the crowd
refused to leave.
2. Use commas
after introductory (a) clauses, (b) phrases, or (c) words that come BEFORE the
Because her alarm clock was broken, she
was late for class.
If you are ill, you ought to see a
(a) Some common starter words for
AFTER, ALTHOUGH, AS, BECAUSE, IF, SINCE,
(While I was eating, the cat scratched
at the door.)
(b) Some common starter words for phrases
VERB + ING
(Having finished the test, he left the
TO + VERB
(To get a seat, you'd better come
LONG PREPOSITIONAL PHRASE (over four
(After the test but before lunch, I went
(c) Some common words preceding a comma:
YES, HOWEVER, WELL
(Well, perhaps he meant no harm.)
3. Use a pair of commas in the middle
of the sentence to set off phrases, clauses, and words that are not essential
to the meaning of the sentence. Use one comma before to indicate the beginning
of the pause and one at the end to indicate the end of the pause.
Can you leave out the clause, phrase, or
word and still have the sentence make sense?
Does the non-essential clause, phrase,
or word interrupt the flow of words in the original sentence?
Can you move the non-essential element
around in the sentence?
4. Does the clause begin with "THAT"?
"THAT" clauses after nouns are almost always essential. "THAT" clauses which
follow a verb expressing mental action are always essential. No comma is needed
in these cases.
"THAT" after nouns:
(The book that I borrowed from you is
(Apples that are green are usually called Granny Smith
"THAT" clauses which follow a verb
expressing mental action:
(She believes that she will be able to
earn an A.)
(He dreams that he can fly.)
(I contend that it was wrong
to mislead her.)
(They wish that warm weather would finally arrive.)
ESSENTIAL: (no comma)
A student who cheats only harms
The girl wearing the tight sweater is
attracting a lot of attention.
NON-ESSENTIAL: (A pair of commas)
Apples, which are my favorite fruit, are
usually harvested in autumn.
Fred, who often cheats, is just harming
Professor Benson, grinning from ear to
ear, announced that the exam will be tomorrow.
Tom, the captain of the team, was
injured in the game.
It is up to you, Jane, to finish.
She was, however, too tired to make the
Two hundred dollars, I think, is
5. Use commas to separate three or more
words, phrases, and clauses written in a series.
Clue: Are the last two items in the series
connected with either AND or OR?
(She couldn't choose between John, Jim,
(The candidate promised to lower taxes, solve the energy shortage,
and end unemployment.)
6. Use commas to separate two or more
coordinate adjectives that describe the same noun.
Can the adjectives be written in reverse
order? (If your answer is yes, add a comma.)
Can you add an AND between the
adjectives? (If your answer is yes, add a comma.)
(a greedy, stubborn child)
(a purple wool shawl)
(an easy, happy smile)
7. Use commas near the end of the
sentence to separate sharply contrasted coordinate elements in the sentence or
to indicate a distinct voice pause.
(He was merely ignorant, not
(You're one of the senator's right-hand men, aren't you?)
8. Use commas to set off middle phrases
at the end of the sentence which refer back to the beginning or middle of the
sentence. These phrases are free modifiers which can appropriately be placed at
the beginning, middle, or end of the sentence without causing confusion for the
CORRECT: Nancy waved enthusiastically at
her parents on the boat, laughing gaily in the process.
INCORRECT: Jane waved at Nancy, laughing
gaily. (Who is laughing, Jane or Nancy?)
9. Use commas to set off all
geographical names, items in dates (except the months and day), addresses
(except the street and number), and titles in names.
(Birmingham, Alabama, gets its name from
(July 22, 1959, was a momentus day in his life.)
(Who lives at 1600 Pennsylvania Avenue, Washington, D.C.?)
(Donald B. Lake,
M.D., will be the principal speaker.)
10. Use commas after "he said," etc. to
set off direct quotations and after the first part of a quotation in a
(John said, "I'll see you tomorrow.")
("I was able," she answered, "to complete the assignment.")
11. Use commas anywhere in the sentence
to prevent possible confusion or misreading.
(To John, Harrison had been a sort of
Commas in the wrong places can chop
ideas into wrong pieces or confuse the reader with unnecessary pauses.
Don't separate a subject from its
The eighteen-year old in California, is
now considered an adult. (INCORRECT)
The most important attribute of a ball
player, is quick reflex actions. (INCORRECT)
Don't put a comma between 2 verbs!
We laid out our music and snacks, and
began to study. (INCORRECT)
I turned the corner, and ran smack into
a patrol car. (INCORRECT)
Don't put a comma before a dependent
(or subordinate) clause when it comes after the main clause (except for extreme
She was late for class, because her
alarm clock was broken. (INCORRECT)
You ought to see a doctor, if you are
(BUT, what happens if the order of the
clauses in these sentences is reversed? See number 2
She was still quite upset, although she
won the Oscar. (CORRECT - EXTREME CONTRAST)
Thanks to the OWL On-Line Writing Lab
at Purdue University.