The ACT English section has hidden patterns, and some of the most common mistakes—comma splices, run-ons, and subject-verb agreement—are exactly the ones you can master before test day. ACT points can be lost on these predictable grammar errors, and we want to help you secure all the points you can! In this post, we’ll break down the ACT grammar rules you must know to boost your score and move with clarity through the aggressive pace of the ACT English test.
What Is Tested on ACT English?
There are two basic question types on the English test: Conventions of Standard English and Rhetorical Skills.
Conventions of Standard English questions assess:
- Punctuation
- Grammar
- Sentence Structure
Rhetorical Skills questions assess:
- Style
- Organization
- Strategy
Today, we will be focusing on grammar, as mastering ACT grammar rules will be an integral boost to your composite score.
Punctuation, Clause Structure, and Agreement ACT Grammar Rules
Dive into the technical must-knows with us in this section!
Comma Splices & Corrections
One of the test’s favorite ACT grammar questions asks how to connect independent clauses. To get started with accomplishing connecting independent clauses, let’s review some sentence structures below:
A simple sentence is made up of a single, independent clause.
- Simple sentences may contain compound subjects, compound predicates, and/or lengthy subject and predicate modifiers, such as adjective and adverb phrases.
A compound sentence is formed when two or more independent clauses are joined together.
- A compound sentence requires punctuation and linking words to join the two independent clauses.
Two types of linking words are used to form compound sentences:
- Coordinating conjunctions. The seven coordinating conjunctions are For, And, Nor, But, Or, Yet, and So.
- Conjunctive adverbs. Conjunctive adverbs express a particular relationship (such as contrast, sequence, or cause/effect) between two ideas.
There are three correct ways to join independent clauses into a compound sentence:
- Comma + Coordinating Conjunction
- Semicolon
- Semicolon + Conjunctive Adverb + Comma
Here are examples in action:
The Incorrect Comma Splice: I studied all week, I passed the test.
A comma splice is not a correct sentence. To correct a comma splice, we can do a few things.
- Correction 1 (Comma + Coordinating Conjunction): I studied all week, so I passed the test.
- Correction 2 (Semicolon): I studied all week; I passed the test.
- Correction 3 (Semicolon + Conjunctive Adverb + Comma): I studied all week; therefore, I passed the test.
Punctuation Mastery
Here are some specific grammar rules for the ACT regarding colons, dashes, and semicolons. Many ACT grammar questions focus on punctuation; knowing when to use a comma versus a semicolon is vital.
- Colons and semi-colons are used to combine independent clauses and offset or indicate lists and series.
- Commas, dashes, and parentheses are used to offset or indicate nonrestrictive information. These clauses could contain extra details that could be removed without changing the core meaning of the sentence.
- Restrictive clauses require no special punctuation as they contain essential details needed to identify the noun they modify.
Example of these grammar rules:
| Rule in Action | Explanation |
| Nonrestrictive (Needs Commas): Sarah Miller, a student from Chicago, scored a perfect 36 on the English section. | The clause “a student from Chicago” is extra information about Sarah Miller. If you remove it, the sentence still makes sense: Sarah Miller scored a perfect 36… Therefore, it is offset with commas. |
| Restrictive (No Commas): The student who scored a perfect score on the English section was offered a full scholarship. | The clause “who scored a perfect score on the English section” is essential to identify which student you are talking about. If you remove it, the meaning changes significantly. Therefore, no commas are used. |
| Semicolon Usage: You must master these three rules before test day; otherwise, your score will suffer due to predictable errors. (Semicolon + Conjunctive Adverb + Comma) I passed the practice test; my confidence immediately improved. (Semicolon to join two closely related independent clauses) | Semicolons are used to connect two complete, independent sentences (clauses) that are closely related in meaning. They are a powerful tool to avoid comma splices and run-on sentences, as you covered earlier. The semicolon replaces the period and makes a stronger connection between the two ideas. |
Run-on Sentences
A run-on sentence is two or more independent clauses joined without the right punctuation and/or linking words.
There are three ways to correct run-on sentences:
- Change one of the independent clauses into a dependent clause to form a complex sentence.
- Separate the independent clauses to form two simple sentences.
- Join the independent clauses with a comma and one of the FANBOYS (For, And, Nor, But, Or, Yet, So), a semi-colon, or a semi-colon and a conjunctive adverb.
For example:
The Incorrect Run-on Sentence: The ACT English test is fast it is important to practice your pacing before test day.
Correction 1 (Complex Sentence): Since the ACT English test is fast, it is important to practice your pacing before test day.
Subject-Verb Agreement
English grammar on the ACT loves to hide the subject behind long prepositional phrases, so it’s very important to understand subject and verb agreement.
- Subject-verb agreement refers to using a verb form that matches or agrees in number with the subject.
- If a subject is singular, its verb must also be singular; if a subject is plural, its verb must also be plural.
- Indefinite pronouns are pronouns that don’t have an obvious antecedent or might not refer to a particular noun. Special care must be taken to make sure that plural indefinite pronouns are paired with plural verbs and singular indefinite pronouns are paired with singular verbs.
For example:
Incorrect Subject-Verb Agreement: The list of essential grammar rules are very long.
Correct Subject-Verb Agreement: The list of essential grammar rules is very long. (The subject is “list,” which is singular and requires the singular verb “is”).
Practice Makes Progress with ACT Grammar Rules
The secret to a high ACT English score isn’t memorizing obscure rules; it’s mastering high-frequency concepts. If you’re ready to move beyond just reading the rules and truly master sentence structure, punctuation, and agreement with hundreds of test-like examples, our ACT course is your next step. We break down complex concepts, such as the comma + coordinating conjunction and the independent/dependent clause relationship, with easy-to-understand explanations and specific practice questions. Take many an ACT English practice test with us and walk into the exam with high-score-earning confidence.
