ACT Grammar Rules Necessary For The Exam

While many think of the ACT as a “sciency” version of the SAT, scoring well on the ACT actually requires a strong understanding of the English language, from reading comprehension skills to being able to identify the flow and organizational structure of a passage. 

Given that half of the ACT English section prioritizes “Conventions of Standard English,” being caught up on grammar will serve you well on test day! This post walks you through an ACT grammar review with essential rules and key ACT grammar tips. 

How Does The ACT English Section Work?

The ACT English section will ask you to revise (or edit) passages by selecting an answer choice that is grammatically correct, concise, clear, and accurate. (Many questions will feature a NO CHANGE option for when the given underlined portion is correct.) These are multiple-choice questions designed to test your writing skills and language ability, divided into three categories: 

  • Production of Writing (29%-32% of questions)
    • For this category, you’ll be considering a piece’s focus and purpose. To score well, you will need to demonstrate an understanding of the rhetorical elements of a passage – its goals, audience, relevance, and focus. 
    • You’ll also be asked to revise for organization, unity, and cohesion, thinking about flow, a passage’s components (beginning, end), and logical structure. 
  • Knowledge of Language (13%-19% of questions)
    • For this category, you’ll be thinking about precision and concision when selecting words. To score well, you’ll need to think about the overall style/tone of the passage, and select words that match the original author’s established style/tone. 
  • Conventions of Standard English (51%-56% of questions)
    • This is where an understanding of key grammar rules really comes into play! To score well in this category, you will apply standard English grammar, mechanics, and typical usage to questions that ask you to edit a text for grammatical accuracy. 
    • Here, you’ll be thinking about the structure and formation of sentences, punctuation, and word usage. 

For each of these categories, the goal is to demonstrate that you have a strong understanding of the English language, and could revise your own work for accuracy, clarity, flow, and tone, just as you revise the given passages.

The Production of Writing and the Knowledge of Language categories require an understanding of composition – what makes a passage easy to follow from beginning to end? What makes a passage compelling, logical, and successful? This section is concerned with writing well, overall. The Conventions of Standard English category, however, is concerned with writing sentences well. 

Keep reading to learn the most important grammar rules for the ACT!

ACT English Section Scoring

On the ACT, you’ll earn a “Test 1 English Score” out of 75 points and a “Test 3 Reading Score” out of 40 points. You can learn more about how ACT scoring works here, but these are a few sample scores at different levels to help you get a sense for what various English/Reading raw scores look like out of 36. 

For a 36/36For a 28/36For a 20/36

Top 10 Grammar Rules For Scoring Well On The ACT

Below, find 10 essential grammar rules you’ll need to know to answer ACT English test questions. 

Rule #10: Fix Redundancy

Often, the ACT will ask that you change an underlined part of a sentence that repeats information you already know. 

  • To answer these problems correctly, you should check for synonyms or repeated ideas. 

Example: My friend Jeremy, who is my friend from Vermont, just arrived at the train station. 

Explanation: We already know Jeremy is a friend, so the underlined portion can be deleted from this sentence. 

Rule #9: Understand Apostrophes (And The Tricky “Its” Vs. “It’s” Situation)

There are three main ways you’ll see apostrophes used in sentences. 

  • To show possession by a singular subject: Lucy’s cat, Yasmin’s new haircut, Bianca’s big promotion at work. Here, the apostrophe follows the subject, and the S follows the apostrophe. 
    • NOTE: When the subject’s name ends with an S – like the name Jess, or apples – you simply place the apostrophe after the final letter, without adding an additional s. 
    • Sample: Jess’ cat, the apples’ peel. 
  • To show possession by a plural subject: the friends’ big trip, the teachers’ day of recognition, the dogs’ toys. Here, the apostrophe comes after the S that indicates plurality. 
  • To indicate a contraction. That is → that’s. It is → it’s. 
    • NOTE: When we’re dealing with the word “its,” you never add an apostrophe to indicate possession. 
    • Sample: “The building lost its electricity today” is the correct way of writing a possessive ‘its.’ 

Example: All forty people who work for We Sell Fish came together for an employee’s picnic. 

Explanation: The underlined word indicates that the picnic is for one employee. Change the sentence to read “All forty people who work for We Sell FIsh came together for an employees’ picnic.” 

Rule #8: Make Sure Your Pronouns/Antecedents Agree 

This grammar concept often requires checking plurality. Plural pronouns should “agree with” (or link to) plural nouns, and the same is true for singular pronouns and singular nouns. 

  • While this may be fairly easy when your sentence is just a few words long, it can be trickier with a wordy sentence. 
  • Tip: As you read, keep track of your subject.

Example: The friends, including the three siblings, Trevor the dog, Bennie’s uncle from New York, and that weird lemon they take everywhere they go, dropped off its textbooks in the classroom. 

Explanation: Because “the friends” is a plural noun, the underlined pronoun should be “their” instead of “its.” 

Rule #7: Use Modifiers Properly 

Misplaced and dangling modifiers appear in writing all the time, and when you actually stop to think about them, they can be kind of funny! Think of a modifier as “extra” information that adds meaning to a sentence. Modifiers should usually appear directly before or after the word they’re modifying. 

  • When modifiers are misplaced, the meaning of a sentence changes. For example, “I ate the sandwich on the train that I bought this morning” should be rewritten as “On the train, I ate the sandwich that I bought this morning.” (I bought the sandwich, not an entire train.)
  • When modifiers dangle, actions can be attributed to the wrong subject. For example, “When playing soccer, Cindy’s cleats injured a teammate” should be rewritten as “When playing soccer, Cindy injured a teammate with her cleats,” or as “When Cindy was playing soccer, her cleats injured a teammate.” (This makes clear that Cindy was playing soccer, not the cleats themselves.)

Example: As they were painting, Ivy’s canvases knocked into Ji-yoo. 

Explanation: This indicates that the canvases were painting, not Ivy and Ji-yoo. To fix this sentence, the underlined portion could be rewritten “As Ivy and Ji-yoo were painting.” 

Rule #6: Be Consistent With Verb Tenses

A sentence should always feature a consistent tense from start to finish. 

  • If your sentence begins in the past tense, make sure all verbs are written in the past tense; the same is true if the sentence is in the present!
  • There are some exceptions to this rule, but they’ll be indicated by the sentence’s meaning. For example, “I grew up wanting to study art, but now I work as a math teacher,” features two verbs in different tenses – grew (past) and work (present). However, this sentence has a “then/now” structure – we’re talking about both the past and present. 

Example: Ahmed ran to the bus stop and drops his lunch. 

Explanation: Because the sentence opens in the past tense, the underlined portion should be changed to “dropped” for consistency in verb tense. 

Rule #5: Brevity (Shortness) Is Your Friend

The key to ‘fixing’ a sentence on the ACT may ultimately come down to using fewer words when given a wordy, difficult to read phrase. 

  • Just like you do with a redundant sentence, check for synonyms or repeated information. 
  • Likewise, decide if some information is unnecessary. 

Example: The professional scientists, who were respected experts in their field, gave a lecture on science. 

Explanation: This entire sentence is underlined because it’s wordy and full of unnecessary, implied information! Rewrite as “The respected scientists gave a lecture.” If you have access to more information (is the lecture on thermodynamics?), swap vague language for specifics whenever possible: “The respected scientists gave a lecture on thermodynamics.” 

Rule #4: Be Careful With Conjunctive Adverbs

Conjunctive adverbs are often used to begin sentences, and their meaning is linked to the sentence that comes before the new sentence. Here are a few conjunctive adverbs: 

Accordingly ThereforeDespiteOtherwise
For exampleAdditionallyLikewiseSimilarly 
FurthermoreHoweverMeanwhileFor instance

Example: Anneke is a good friend of mine. However, we never fight. 

Explanation: These two sentences do not disagree – one builds upon the other. For this reason, the underlined word should be replaced with “Accordingly,” “Therefore,” “Consequently,” “Subsequently,” or another conjunctive adverb that demonstrates agreement.

Example: The rain is definitely coming. Subsequently, the show must go on. 

Explanation: As it stands, the underlined conjunctive adverb indicates that the latter sentence is the direct result of the former sentence. The underlined word should be changed to “However” or “Regardless” to indicate that the show will go on despite the rain. 

Rule #3: Know Idioms and Verbal Phrases 

Standard American English is full of idioms, or phrases with figurative meaning that isn’t directly implied by the phrase itself. You’ve probably heard somebody say “It’s raining cats and dogs,” or “I’m totally in the dark about this.” These are idioms, and knowing a few common idioms may be useful for the ACT English section. 

Likewise, verbal phrases are a type of idiom that feature a verb paired with a preposition, like “carry on” (continue) or “take over” (take control). 

Below, find idioms and verbal phrases you may come across on the test. 

  • Bite the bullet (give in)
  • Break a leg (good luck)
  • Call it a day (give up)
  • Hang in there (keep going)
  • It’s not rocket science (it’s simple)
  • On the ball (doing well)
  • Pull it together (be calm)
  • Get in 
  • Responsible for
  • Take off
  • Put back
  • Look around
  • Refrain from
  • Take in
  • Set down
  • Followed by
  • Move up

Rule #2: Understand Colons, Semicolons, and Em Dashes

When connecting clauses with punctuation, errors most frequently pop up when students use colons, semicolons, and em dashes. Knowing which punctuation to use depending on the given sentence will be essential for your ACT cheat sheet: 


  • Colons are used to indicate a list. For example, “I love all types of weather: rain, shine, fog, and wind!” 
  • Colors are also used to indicate an example, definition, or explanation is about to follow the previous statement. For example, “Today is a great day: the clouds have parted.” (This is an explanation of why today is great.)


  • Semicolons are used to separate two independent clauses without the use of a conjunction. For example, “My back hurts today; I’ve been in bed for hours.” 
  • Semicolons are also used when writing a list where one list item features a comma. For example, “For vacation, I’m packing my sunglasses; my large, wide-brimmed hat; my purple bikini; my lemony, SPF 50 sunscreen; and my nice sandals.” 

Em Dashes

  • Em dashes are used similarly to parentheses, inserting additional information into a sentence that, if removed, would not change the sentence’s meaning overall. If the extra information appears in the middle of the sentence, you’ll always use two em dashes on either side. For example, “I really miss my dog – she’s been a good friend to me – and this hotel room smells awful.” 

Example: I’m going home, the food here sucks. 

Explanation: Because the latter clause is an explanation, this sentence should be fixed with a colon. “I’m going home: the food here sucks.” 

Example: Sometimes – usually when it rains; I feel sleepy and lethargic. 

Explanation: Because this extra information falls in the middle of a sentence, it should be surrounded by two em dashes. The correct sentence would read, “Sometimes – usually when it rains – I feel sleepy and lethargic.” 

Example: My professor suggested I take a semester abroad, she said the weather in France is nice in the spring!

Explanation: Because these are two independent clauses, we cannot separate them with only a comma. Instead, use a semicolon to separate independent clauses. “The professor suggested I take a semester abroad; she said the weather in France is nice in the spring!” 

Rule #1: Understand Complex Comma Usage

This rule is more like several smaller rules combined into one! Commas are tricky – you probably see comma mistakes in professional writing all the time. Understanding the various different ways commas are used (and when NOT to use commas) will serve you well on the ACT. 

  • Use commas to separate items in a list. When you’re separating items in a list that do not have commas within them already (see semicolon usage above), you simply connect them with commas and a conjunction at the end. 
    • “Sasha hopes to take bio, chem, and physics her freshman year.” 
  • Use a comma and a conjunction to combine independent clauses. If you’re working with two independent clauses – or sentences that can stand alone – you connect them with a comma and a conjunction, also known as a “FANBOY” (For, And, Nor, But, Or, Yet). 
    • “My sister arrived at seven, but I arrived around eight.”
  • Use commas after prepositions. If your sentence opens with a prepositional phrase (words that indicate time, location, and direction, or introduce an object), follow that phrase with a comma. 
    • “In the afternoon, my package will arrive.” 
    • “When the sun rises, my dog will start barking.” 
    • “After the storm, we can ride our bikes.” 
    • “Under the sofa, you’ll find a lot of dust!” 
  • Use commas before/after non-restrictive clauses. A non-restrictive clause is information that adds to a sentence but could be removed without changing the sentence’s meaning. These clauses should be surrounded by commas. 
    • “My best friend, given her allergies, didn’t come with me to the cat cafe in Seattle.” 
      • Here, “given her allergies” doesn’t really change what the sentence is saying, so it is a non-restrictive clause and surrounded by commas. 
    • Note: A restrictive clause is essential in a given sentence – removing it would inherently change the meaning. You don’t need to surround restrictive clauses with commas. 
  • Use commas before/after an appositive. An appositive is a word or phrase that further describes/defines the noun that comes directly before it, and appositives are surrounded by commas. 
    • “Zendaya, a celebrity, will be giving the speech.” Because this sentence could read “Zendaya will be giving the speech” and still be clear and logical, ‘a celebrity’ is an appositive.
      • Note: The sentence “Celebrity Zendaya will be giving the speech” would not feature commas, because here the “Zendaya” part is essential information – otherwise, we wouldn’t actually know who would be speaking.” 
    • My dentist, John Weaver, is always really nice to me.” 

Other Grammar Concepts To Understand For The ACT

Beyond the key grammar rules, here are a few additional topics to brush up on before the test: 

That, Who, Whose

The word “that” generally refers to objects, whereas “who” and “whose” refer to people. 

Example: “Mina, whose test results just came back, needs to log into the portal.” 

Example: “Jonas, who you met last week, is coming to stay again.” 

Sentence Fragments 

When sentences are missing subjects or begin with completing phrases, we end up with sentence fragments. Make sure sentences have both subjects and verbs! 

Sample fragment: “Jumped on a train.” (WHO jumped on a train?)

Sample fragment: “Although it rained.” (‘Although’ makes this sentence a fragment – although what?)

Run-On Sentences

These occur when two (or more) independent clauses aren’t connected with proper punctuation, like a semicolon or ‘and + FANBOY.’ 

Example: I was going to the mall and my sister wanted new shoes and I wanted a pretzel. 

Common Mistakes 

Brush up on these commonly confused words – they may appear on the ACT!

  • Accept vs. Except
  • Affect vs. Effect
  • Allude vs. Elude
  • Allusion vs. Illusion
  • Cite vs. Sight vs. Site
  • Complement vs. Compliment 
  • Elicit vs. Illicit
  • Eminent vs. Imminent 
  • Ensure vs. Insure
  • Lay vs. Lie
  • Lead vs. Led
  • Loose vs. Lose
  • Passed vs. Past
  • Precede vs. Proceed 
  • Than vs. Then
  • Their vs. There vs. They’re
  • To vs. Too

How To Study For The ACT English Section

Beyond making sure you understand each of the rules from this blog post, one of the best ways to study for the ACT English Section is to simply read and write! Additionally, taking ACT practice tests will help you figure out timing and a general idea of what your test score might be; you could also work with a tutor or form a study group. 

Sample ACT English Section Questions

Check out these questions for more ACT review – they come directly from the ACT and will give you a sense for how the test is structured and what these key grammar concepts look like in action. 


The English portion of the ACT test may be tricky – the average score is about 42 questions answered correctly out of 75 – but arriving on test day confident in your grammatical ability will make a big difference as you evaluate the passages provided by the ACT. Review the rules in this post, practice by reading and writing, and be on the lookout for grammatical errors in your daily life (cereal boxes, bathroom signs). Good luck!

Improve Your Score With SoFlo Tutors

If you or your student is looking for help studying for the test with a qualified and friendly tutor, SoFlo’s Online Tutoring is a great resource for one-on-one tutoring with college students who excelled on their own ACTs, retain familiarity with the material, and know key techniques to make taking the ACT a better experience. 

With SoFlo, students have flexibility with scheduling, session structure, and homework. SoFlo students see noticeable performance results – consider scheduling a free consultation


About the Author  

Renée Flory

Renée Flory studies professional & creative writing and English literature at Johns Hopkins University. She scored a 1570 on the SAT, and in her free time enjoys writing novels.

You may also like

Comments are closed.