Commas have been the source of countless headaches, since the rules governing their use can be a bit difficult to remember. In some cases the rules seem murky and inconsistent. Just look up “oxford comma” and you’ll find a whole world of conflict! That said, the English language does have several consistent rules for using commas, and that is what the ACT will focus on. You likely already know most of these, even if only intuitively. Use the table below to ensure you’re familiar with all of the comma rules you might encounter on the exam.
Rule
Example
Separate items in a list
In a list of three or more items, use commas to separate each of them, place and before the last item.
Example
I will need to study for exams in biology, history, and math.
This rule applies to phrases as well
Example
The professor said the students should focus on learning to communicate with others, applying critical thinking strategies, and developing strong written work.
Separate two or more coordinating adjectives
When there are two adjectives in a row that both describe a noun, use and or a comma to separate them.
Correct ✅
She immediately fell in love with the tiny, fuzzy puppy.
She immediately fell in love with the tiny and fuzzy puppy.
Incorrect 🚫
She immediately fell in love with the tiny fuzzy puppy.
ExceptionWhen a number is used as an adjective in front of another adjective, then DO NOT use and or a comma. This is an example of cumulative adjectives, rather than coordinating adjectives.
Correct ✅
The marine biologist placed the four slimy eels into separate tanks.
Incorrect 🚫
The marine biologist placed the four, slimy eels into separate tanks.
Separate out dates and locations
They moved to Los Angeles, California, in 2005.
On August 28, 2023, she began her first semester of college.
Set off direct quotations
When a quote is attributed to a person with a signal phrase, use a comma to set it off.
Examples
Richardson claimed, “additional extracurricular activities should be offered to new students.”
I’ll be there as soon as I can,” she said.
“If we don’t want to be late,” said Felicia, “we’ll need to leave by 4 o’clock.”
Note that when the signal phrase comes after the quote, the comma is placed inside the quotation marks. When the signal phrase appears in the middle of the quote, the first comma is placed inside the quotation marks.
Indicate direct address
When naming the person to whom a statement is directed, use a comma to set it off. The comma will be after the name if at the beginning of a sentence, before the name if at the end of the sentence, and on either side if in the middle.
Examples
Chris, I believe you are correct.
I believe you are correct, Chris.
Yes, Chris, I believe you are correct.
Connect two independent clauses with a coordinating conjunction
Independent clauses can be joined by a comma + coordinating conjunction.
Examples
We decided to look for art classes in our area, but we knew that it might be difficult to find one.
The school offered to increase the number of elective courses, and a survey of the students indicated they were in favor of this.
Note that independent clauses should never be joined by a comma alone—this error is called a comma splice.
Connect an introductory (dependent) clause to an independent clause
A dependent clause at the beginning of a sentence is referred to as an introductory clause and should be followed by a comma.
Examples
Before we leave, I need to feed the cats.
Although they’ve been working together for several years, Rick and Lamorne only recently became friends.
Set off a nonrestrictive/ nonessential clause
Commas should be used on either side of a clause that is not essential to the meaning of the sentence.
Examples
The community garden, which is a mile from my house, has flowers and vegetables.
Dr. Sanchez, who moved to Chicago last year, said he would support the policy.
Set off an appositive
Appositives are nouns or noun phrases that provide extra information about another noun. When appositives are not essential to the meaning of the sentence, they can be set off by commas just like nonrestrictive clauses.
Examples
Ms. Smith, a former teacher, will be the keynote speaker at this year’s conference.
Her dissertation addresses the work of James Baldwin, a writer and civil rights activist.
When an appositive is essential, however, do not use commas—just like restrictive clauses.
Example
My friend Jan will be coming over later.
Set off question tags
That book is fantastic, isn’t it?
You’re auditioning for the play, right?
You didn’t leave your keys at home, did you?
How Will the Test Try to Trick You?
The test will include several items that require you to determine whether or not commas are being used correctly. The examples below are some of the most common issues you’ll encounter.
Examples
Incorrect 🚫
Correct ✅
Sentences with comma splices
This sentence contains a comma splice—ONLY a comma is used to separate the two independent clauses.
Soccer is a fun sport, it is filled with action.
The clauses must be joined with a conjunction, a comma + conjunction, a semi-colon, or a colon.
Soccer is a fun sport because it is filled with action.
Soccer is a challenging sport, and it requires years of training.
Soccer is great exercise; it involves a lot of running and footwork.
Our soccer team holds one rule above all else: have fun.
Commas separating essential clauses or phrases
I go to the park, that has the community garden, at least once a week.
The red shirt, with the flower design, is my favorite.
My coworker, Aparna, will drive me home today.
I go to the park that has the community garden at least once a week.
The red shirt with the flower design is my favorite.
My coworker Aparna will drive me home today.
Missing commas
Because they have such busy schedules most student athletes don’t have time to join clubs.
“I have never seen that movie” said Martha.
He gave an informative intelligent speech.
Because they have such busy schedules, most student athletes don’t have time to join clubs.
“I have never seen that movie,” said Martha.
He gave an informative, intelligent speech.
Tips and Strategies
Spend time familiarizing yourself with the rules for comma usage.
Review and practice several examples.
When you see a comma, determine the following:
What function is the comma serving in the sentence?
Are the clauses before and after the comma dependent or independent?
Are the clauses essential or nonessential? Restrictive or nonrestrictive?
Does the comma disrupt or support the structure of the sentence?
