The Must-Know Comma Rules for the ACT

  • Updated December 12, 2024

Commas. We love them. We hate them. And, sometimes, don’t, know, when, to, use, them. 

No matter how much we dislike commas, it’s hard to argue against their importance, including on the ACT. Take these two sentences for example:

“Let’s eat, Grandma.”
“Let’s eat Grandma.”

Without the comma, Grandma would be in big trouble come dinnertime.

Knowing when and how to use commas the key to a higher ACT score. In fact, comma usage makes up 20% of your English score. It’s important to familiarize your students with all the grammar rules concerning commas so that they are prepared for this high-stakes assessment.

  • 6 Important Comma Rules for the ACT

Below are six guiding principles for understanding commas on the ACT, drawing on insights from the MasteryPrep Boot Camp for the ACT.

  • When in doubt, commas out:
If you must blindly guess on a punctuation question, eliminate the obvious run-on sentences, then go with the choice that uses the fewest commas.
  • Removing (rather than adding) commas is the norm on the test:

On the ACT, you’ll often need to remove unnecessary commas rather than add essential commas.

  • Commas are used to separate ideas:

Commas separate independent clauses when linked with a coordinating conjunction. Coordinating conjunctions can be remembered by the acronym FANBOYS: for, and, nor, but, or, yet, so. For example:

INCORRECT: He shined his shoes and his friends waited in the living room.
CORRECT: He shined his shoes, and his friends waited in the living room.

  • Commas cause pauses:

Commas mark a brief pause in the sentence. The place where the comma is at indicates a natural pause when reading the sentence aloud. If the pause is missing, get rid of the comma!

  • No solo comma:
You shouldn’t have one solitary comma between a subject and its verb. Two commas may separate the subject and verb to mark an interrupting thought, but just one comma is an error. For example:

INCORRECT: The soft cat, ready for a nap jumped on the couch.

INCORRECT: The soft cat, jumped on the couch.

CORRECT: The soft cat jumped on the couch. (no commas between subject and verb)

CORRECT: The soft cat, ready for a nap, jumped on the couch.

  • Use commas to set off non-essential phrases from the part of the sentence they modify, but don’t use commas for essential phrases. For example:
Non-Essential:

INCORRECT: My uncle who lives far away is coming to visit for Thanksgiving.

CORRECT: My uncle, who lives far away, is coming to visit for Thanksgiving.


Essential:

INCORRECT: The movie, that played in the park, was one of my favorites.

CORRECT: The movie that played in the park was one of my favorites.

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