ACT English Grammar – Comma Rules


ACT English Grammar – Everything You Need To Know About Comma Rules

ACT English Grammar - Comma Rules

YoNo one likes commas – they’re confusing and weird, but if you want to succeed on ACT English, you have to learn how to become a comma usage expert because commas happen to be ACT’s favorite punctuation to test.

Luckily, there is a relatively short set of comma rules you will need to know for the ACT and in this article, we will discuss:

  • The Most Important Comma Rule
  • 4 Main Rules for Comma Usage on ACT
  • When NOT to use a Comma

When in Doubt, Leave It Out!

ACT English Grammar – Everything You Need To Know About Comma Rules

This is the most important comma usage rule for the ACT: if you are not sure if a comma is necessary, then you probably don’t need one. In fact, you are far more likely to miss a question by adding an unnecessary comma than you are by leaving a comma out.

Here is an example from a real ACT test:


If you only read the underlined portions, it may be tempting to add a comma after “officials” or keep the comma after “value”. However, the sentence is perfectly clear without either of the commas, making H the correct choice.

The same rule applies to this example:


This sentence makes perfect sense without either of the commas around the phrase “this legacy of letters.” In addition, having two commas around a clause makes it act as a “non-essential clause” which, by definition, can be taken out without changing the meaning of the sentence. If we take out the phrase “this legacy of letters,” we will be left with “Perhaps explains what she meant when she said that her friends….” which is a fragment, so again, no commas are necessary. D is the correct answer choice.


Correct punctuation can save someone’s life

4 Main Rules for Comma Use on the ACT

ACT English Grammar – Everything You Need To Know About Comma Rules

The basic purpose of a comma is to clarify the relationship between phrases and clauses. This is a very broad description and there are many, many comma rules; however, to do well on the ACT, you must focus your studying on these four main rules:

  • Modifying phrases and clauses through the use of appositives, relative clauses, and interjections
  • Introductory phrases and clauses
  • Connecting independent clauses with a conjunction
  • Separating items in a list

Let’s talk about each rule in more detail.

Appositives, Relative Clauses, and Interjections

ACT English Grammar – Everything You Need To Know About Comma Rules

As a rule, any part of a sentence that can be removed without changing the meaning of a sentence must be surrounded by commas.

For example,

Johnny who loves the Avengers is excited about the upcoming movie.

The main point of the sentence is that Johnny is excited about a movie – his love of Avengers is just extra background information that helps explain why Johnny is excited about the movie but is not necessary for the sentence to make sense. Since “who loves the Avengers” does not affect the main point of a sentence, we can separate this clause from the rest of the sentence by placing commas on either side of the phrase:

Johnny, who loves the Avengers, is excited about the upcoming movie.

To check if a part of the sentence should be surrounded by commas, try crossing it out. If the sentence retains its original meaning, then commas are needed; if it doesn’t, then commas are not needed.

Let’s look at another example:

The student who forgot his homework got detention.

At first glance it seems that the phrase “who forgot his homework” should be offset by commas. If we cross this phrase out, we get:

The student who forgot his homework got detention.

With the clause “who forgot his homework” crossed out, it is no longer clear which student got detention, so by removing that clause, we have changed the meaning of a sentence. That means that the sentence does not need commas because it is referring to a specific student “who forgot his homework”.

Keeping these general principles in mind, let’s discuss three specific cases:

Relative Clauses: Restrictive vs. Non-Restrictive

ACT English Grammar – Everything You Need To Know About Comma Rules

Relative clauses are dependent clauses that describe a noun and start with a relative pronoun or adverb such as “which,” “that,” or “where.” If you are not sure exactly what any of those terms mean, consider reading our article on fragments and run-on sentences.

  • Restrictive clause – clarifies the specific thing you are talking about, so you do not need to use commas around it.
  • Non-restrictive clause – comments on an already clearly defined noun so it needs to be offset with commas.

Restrictive clause:

These clauses are essential to the meaning of the sentence, they explain exactly what or who the sentence is talking about. If you take a restrictive clause out of a sentence, you will change its meaning fundamentally. For example:

People who like to stay at home won’t enjoy loud parties.

In this sentence, if you take out the clause “who like to stay at home,” you’ll be left with “People won’t enjoy loud parties.” The original sentence explains that homebodies won’t enjoy noisy events, but the altered sentence says that people (in general) won’t enjoy loud parties. The meaning of the sentence changes with the removal of the clause. 

Rule: Because this kind of clause cannot be removed without changing the meaning of the sentence, it should not be offset with commas.  

Non-restrictive clause:

These clauses provide additional information and, therefore, are not integral to the meaning of the sentence.

My brother, who dislikes classical music, won’t enjoy the opera.

The point of this sentence is that my brother doesn’t enjoy opera. Even if you remove the underlined potion, that point is still made. Unlike in the above example, if you remove the non-restrictive clause, the meaning of the sentence does not change, therefore, a non-restrictive clause should be offset with commas.

Important point of the ACT: clauses that start with “which” are always non-restrictive, while clauses that start with “that” are always restrictive. This means that “which” always takes a comma and “that” never does. 

All students that study for the ACT should get a strong score.

Puerto Rico, which was a Spanish colony, was ceded to the United States in 1898.

Appositive Phrases

An appositive is a noun or noun phrase that describes another noun or pronoun that is right next to it and does not include a verb. The appositive can be a short or long combination of words.

The comma rules are identical: if a word or phrase can be removed without changing the meaning of the sentence, it must be offset by commas.

Let’s look at some examples:

The insect a large cockroach is crawling across the table. à The insect, a large cockroach, is crawling across the table.

The New York Times the newspaper first appeared in the 1850s. à The New York Times, the newspaper, first appeared in the 1850s.

The nouns “a large cockroach” and “the newspaper” modify “the insect” and “The New York Times” respectively, but they are not necessary to the main point of the sentence.

Appositive Phrases(cont’d)

A somewhat confusing variation of this rule is when the order of appositives is reversed, they don’t usually need a comma. For example:

Frank Lloyd Wright, an architect, designed many buildings including the Guggenheim Museum.

Architect Frank Lloyd Wright designed many buildings including the Guggenheim Museum.

In the first example, “an architect” describes Frank Lloyd Wright. Without the appositive, we still understand from this sentence that Frank Lloyd Wright designed many buildings, so commas are necessary around “the architect.”

In the second example, “the architect” comes first and still modifies “Frank Lloyd Wright” but if we offset the name with commas the sentence will read “Architect designed many buildings including the Guggenheim Museum,” but will not clarify which architect.  So, no commas are needed. It might be tempting to add a comma after architect, but it is actually acting like an adjective in this construction. Just like you wouldn’t put a comma in the middle of “President George Washington,” or “Author Margaret Mitchell,” you shouldn’t add one in “Architect Frank Lloyd Wright.


Interjections are words or short phrases like “however” or “of course” that disrupt the flow of a sentence. ACT does not test them as frequently as they do appositives and relative clauses, but questions about interjections do come up occasionally. If this concept does get tested, it will usually be in the form of a transition word that is moved into a sentence. For example:

Yay, it’s finally Friday and the work week is over.

It is so exciting, my goodness, I just can’t believe it.

My brother, however, refused to help me with homework.

As a rule of thumb remember that if a transition word appears in the beginning or the middle of a sentence, it must be offset by commas.

Important: If something is surrounded by commas, then it is not important to the main point of the sentence. If it is important, then no commas are needed.  

ACT Example

ACT questions about appositives usually test whether a comma is needed and if so, where it should be placed.


As written, this sentence does not have a main verb, only a subject “Houdini” followed by a long non-restrictive clause; therefore, F cannot be right. J and it’s out because it doesn’t solve the problem and it gets rid of the verb “was.” G and H both put a comma after “spiritualism,” which gives us the non-restrictive clause “who devoted considerable effort to exposing hoaxes involving spiritualism.” If you cross it out, you get either:

  1. Houdini, who devoted considerable effort to exposing hoaxes involving spiritualism, being skeptical about the existence of supernatural beings.


  1. Houdini, who devoted considerable effort to exposing hoaxes involving spiritualism, was skeptical about the existence of supernatural beings.

Comparing these two options side by side you can clearly see that H is the right choice. The word “being” in option G is not a correctly conjugated verb. In fact, answers with “being” are almost always wrong. For a more in-depth explanation of this concept and other helpful tips read our article on ACT English tips.

The key to answering this type of question correctly is determining what belongs in the non-restrictive relative clause and then making sure that what is left outside of the relative clause adds up to a grammatically correct sentence.


ACT English Grammar – Everything You Need To Know About Comma Rules

So far, we’ve discussed rules about comma usage with phrases and clauses inside the main clause of the sentence. Now we will discuss when you need commas to separate phrases and clauses that come in the beginning of a sentence. In short, the answer is: Always.

Rule: any time a sentence starts with a dependent clause or modifying phrase, it must be followed by a comma.

            Before the movie starts, let’s get some popcorn.

Even though I was tired, my friends convinced me to go out.

During the production of the film, the director nearly quit.

In each of these examples, the underlined phrase serves to introduce an independent clause. Notice, however, that if you change the order of the sentence, you won’t need the comma anymore

Let’s get some popcorn before the movie starts.

My friends convinced me to go out even though I was tired.

The director nearly quit during the production of the film.

ACT Example

The ACT rarely tests introductory clauses directly. Instead, this concept is usually tested when you are asked to combine multiple phrases or clauses or in questions that have multiple clauses strung together.



Here, “the next morning” is an introductory phase that should be set off with a comma, so D is out. Choice C uses a semi-colon incorrectly. Recall that semicolons are used after an independent clause that can stand on its own as a sentence. For more detailed explanation, read our article about semicolons and other punctuation.  “The next morning, using twigs for kindling;” is not an independent clause, so C is out. Now we have to decide which relative clause should be surrounded by commas – “using twigs” or “using twigs for kindling.”

ACT Example(cont’d)

Let’s consider each option using the strikethrough method from the previous section:

  1. The next morning, using twigs, for kindling she starts a small blaze in the firebox, located directly below the main chamber.


  1. The next morning, using twigs for kindling, she starts a small blaze in the firebox, located directly below the main chamber.

B is obviously correct because it correctly punctuates both “the next morning” and “using twigs for kindling.”

As stated above, when dealing with commas always remember that when you surround something with commas, you’re telling the reader that it can be removed without changing the meaning of the sentence.  

Here, the main point of the sentence is that she started a fire and the clause “using twigs for kindling” clarifies how she started the fire. It can be removed without altering the main point of the sentence.

Connecting Independent Clauses with a Conjunction

ACT English Grammar – Everything You Need To Know About Comma Rules

Rule: If you have two independent clauses and want to combine them into one sentence, you can use a comma with a coordinating conjunction, or FANBOYS (for, and, nor, but, or, yet, so) instead of a semicolon.

Jessica wanted to go on vacation, but she had to take a summer class.

Remember: using only a comma (no coordinating conjunction, i.e. FANBOYS) to combine two independent clauses creates a comma splice and is always wrong. A comma is not interchangeable with a semicolon, but it is one of the most common errors students make on ACT English.

Incorrect:         I didn’t like the movie, it was way too long.

Correct:           I didn’t like the movie; it was way too long.

Correct:           I didn’t like the movie, and it was way too long.

On the ACT, this comma rule is never tested alone. Instead, it is usually tested in the context of other types of punctuation or in terms of identifying independent and dependent clauses. For more information on this, see our article about correctly connecting independent clauses.


ACT English Grammar – Everything You Need To Know About Comma Rules

The comma rule involving lists is the one you are probably most familiar with: lists of 3 or more items must be separated by a comma after each item.

Examples:       We have to pick up Kevin, Mike, and Jessica from the airport.

I went to the store to buy some apples, oranges, and grapes

Note, in many English classes there is an ongoing debate on whether or not to use an “oxford” comma (the comma that goes before the “and”); however, you must use it on the ACT English.

 Lists of Two Items

The ACT will not give you lists of items without any punctuation. Instead, they will try to trick you in much more subtler ways. If, after reading everything up to this point, you developed an idea that you must put a comma every time you see an “and” (or any other coordinating conjunction), remember that that is NOT true. If a coordinating conjunction connects two things that are not independent clauses, then you do NOT need a comma.

Example:         Martha and her sister travelled to Spain and Portugal.

The ACT loves to trick students with seemingly simple list questions by making each item so long that it no longer looks like a list.

Example:         To survive another boring lecture, James tried to drink an extra strong cup of coffee before class and emptied sugar packets in his mouth when the professor wasn’t looking.

Neither one of the above examples needs a comma because they are lists of only two items.

Lists of Adjectives

This is a somewhat different type of list, but it does come up sometimes on the ACT English.

Rule: For a list of two or more adjectives: if the order of the adjectives does not matter, separate them with commas. If the order does matter, you do not need a comma.

Examples:       Florida is a hot humid state.

She bought an ugly plastic ornament.

If you are not sure which one of the examples needs a comma, try switching the order of adjectives:

Examples:       Florida is a humid hot state.

She bought a plastic ugly ornament.

The first example can be in either order, so commas are necessary to separate the adjectives: “Florida is a hot, humid state.” The second example sounds awkward when we switch the order of adjectives, so we do not need a comma.

ACT Example

Here is an example from real ACT that demonstrates this rule:



At first, it seems tempting to add a comma before “and,” however this sentence is correct as written. The underlined part is a list of two things: “her labor” and “fire’s magic”. The other choices just complicate the sentence. This sentence also deals with parallelism because the word “results” applies to both “her labor” and “fire’s magic.”

If you are not sure whether to add a comma, remember the main rule: When in doubt, leave it out.

When to NOT Use Commas

ACT English Grammar – Everything You Need To Know About Comma Rules

Up until now, we have spent a lot of time talking about when to use commas, but now we’re going to approach this topic from an opposite direction and talk about when to NEVER use commas. You should never use commas to separate a subject and a verb, before or after a preposition, or around an emphatic pronoun.

Let’s discuss these in more detail.

NO Comma:

Between a Subject and a Verb

The whole point of using commas is to separate and clarify relationships between different clauses, so a comma should never be placed in the middle of a single clause.

Example:         I, went to the market. à I went to the market.

While this example is very straightforward, sometimes it’s not so easy to tell if a comma is out of place:

Example:         Listening to a boring lecture, was annoying. à Listening to a boring lecture was annoying.

The comma is not necessary in this sentence: “listening” is the subject and “was” is the verb. The reason this comma usage seems more complicated is because it is easy to confuse “listening to a boring lecture” with an introductory phrase that would require a comma. If this were an introductory phrase, the main clause would have its own subject and verb (ex: listening to the boring lecture, I feel asleep) and that is not the case here, so no comma is necessary.

Before or After a Preposition

On the ACT English, it is NEVER correct to place a comma before or after a preposition.

Example:         Neither of these cookbooks contains the recipe I am looking for.

The plump, red tomatoes on the kitchen counter look ripe and delicious.

It may seem appropriate to place commas before or after preposition phrases, but the commas are not necessary because they add confusion to the sentences.

Warning: Sometimes, the ACT uses preposition phrases to break apart the subject and the verb of the main sentence. In that case, the prepositional phrases must be punctuated.

Example:         Tommy, along with other students, breathed a sigh of relief when he found that the test was postponed.

Here, the verb breathed relates to the subject of the sentence “Tommy,” not “other students.” It is important to remember that the prepositional phrase never contains the subject of the sentence.

Before or After an Emphatic Pronoun

Emphatic pronouns (aka: reflexive pronouns) are myself, yourself, itself, herself, himself, ourselves, themselves, and yourselves. They are used immediately after a noun or another pronoun.

Examples:        She will do it herself.

I heard the story myself.

Although the construction may seem like they need a comma, a comma should never surround an emphatic pronoun.

Incorrect:         The Queen, herself, attended the wedding.

Correct:           The Queen herself attended the wedding.

The ACT English section frequently tests this obscure rule, so it’s worth your time to memorize and apply it.

Next Steps

Does the content of the ACT English section confuse you? Read our article about what the ACT as a whole and the ACT English section cover.

After reading this article you should be feeling confident about punctuation; however, are you comfortable with vocabulary words that the ACT tests? If not, here’s a guide for you.

ACT English section asks the same types of questions over and over. As you take and review practice tests, try increase your effectiveness by understanding why you missed each question.

If you would like to watch a video where I talk about everything written int his article, please follow this YouTube link.

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