ACT English Section: 20 Grammar Rules You Must Know to Score 34+
2026-04-30-3 · 12 min read
Introduction: Why Grammar Rules Matter on the ACT
The ACT English section tests your command of grammar, punctuation, and style across 75 questions in 45 minutes. Unlike the SAT, which emphasizes reading comprehension, the ACT focuses heavily on grammatical knowledge. Scoring above 34 on this section (75th percentile) requires mastering core grammar rules that appear repeatedly throughout the test. Research shows that students who understand foundational grammar rules improve their ACT English scores by an average of 3-4 points. This article breaks down 20 critical grammar rules you must know, with real examples and practical applications. Whether you're aiming for a top-tier university or simply want to boost your composite score, these rules form the backbone of test success.
Subject-Verb Agreement and Pronoun-Antecedent Consistency
Subject-verb agreement appears in approximately 8-10% of ACT English questions. The rule is straightforward: singular subjects require singular verbs, and plural subjects require plural verbs. The challenge lies in identifying the true subject when clauses intervene. Example: "The group of students are studying" is incorrect; "The group of students is studying" is correct because "group" is the singular subject. Similarly, pronoun-antecedent agreement requires pronouns to match their antecedents in number and gender. Incorrect: "Each student should submit their assignment." Correct: "Each student should submit his or her assignment" or "All students should submit their assignments." Watch for collective nouns (team, committee, audience) which are typically singular in American English. The ACT frequently tests these rules with intervening phrases designed to confuse test-takers. To practice, identify the subject before choosing your verb form, and underline antecedents to verify pronoun agreement. This single rule category can account for 5-8 questions on your test.
Comma Splice, Run-On Sentences, and Sentence Fragments
Comma splices occur when two independent clauses are joined by only a comma. Incorrect: "The weather was beautiful, we decided to go hiking." Correct: "The weather was beautiful, so we decided to go hiking" or "The weather was beautiful; we decided to go hiking." Run-on sentences incorrectly join independent clauses without punctuation: "The weather was beautiful we decided to go hiking." Sentence fragments lack a subject or verb: "Because the weather was beautiful." The ACT tests these errors extensively—expect 6-8 questions per test. Solutions include using coordinating conjunctions (FANBOYS: for, and, nor, but, or, yet, so), semicolons, periods, or creating dependent clauses. Fragments are sometimes intentional for stylistic effect, but on the ACT, they're errors unless in dialogue. A helpful strategy: read each sentence aloud to your internal ear. If it sounds incomplete or awkwardly connected, it likely contains an error. Many test-takers miss these because they read too quickly. Slow down, identify clause boundaries, and verify each sentence is complete and properly connected.
Apostrophes, Parallelism, and Modifier Placement
Apostrophes indicate possession or contraction—a seemingly simple rule that tricks many students. Use apostrophes for possessives: "John's book," "the students' classroom," "its purpose" (not "it's"). Remember: "it's" is always "it is" or "it has." Parallelism requires that items in a series share the same grammatical structure. Incorrect: "She enjoys reading, writing, and to paint." Correct: "She enjoys reading, writing, and painting." Misplaced and dangling modifiers create confusion. A modifier should clearly relate to the word it modifies. Incorrect: "Walking to school, the rain began to fall." Correct: "As I walked to school, the rain began to fall." The ACT includes 4-6 questions on these topics combined. Test-takers often overlook modifier placement because the sentences seem grammatically acceptable at first glance. However, logical meaning requires that modifiers be placed near the words they modify. Read each sentence carefully, and ask: "What does this modifier refer to?" If the answer is unclear, it's likely an error. Practice identifying the sentence's core structure—subject, verb, object—then verify all modifiers attach logically.
Verb Tense Consistency and Complex Sentence Structure
Verb tenses must remain consistent unless the timeline logically shifts. Incorrect: "She walks to the store and buys milk yesterday." Correct: "She walked to the store and bought milk yesterday." The ACT frequently tests tense shifts within complex sentences involving multiple clauses. Master these structures: simple (one independent clause), compound (two independent clauses joined by a conjunction), and complex (at least one dependent clause). Subordinating conjunctions (because, although, while, since, if) introduce dependent clauses and establish time relationships. Example: "Because she was late, she missed the beginning." Notice how the subordinating conjunction clarifies the relationship between actions. Expect 5-7 tense-related questions per test. When reviewing answers, check each verb's tense and verify it matches the timeline and other verbs in the passage. Additionally, watch for conditional statements ("If I were..." not "If I was...") and subjunctive mood requirements. These nuances distinguish high scorers from average performers. Practice by rewriting sentences with different tenses and noting how meaning changes.
Additional Critical Rules: Articles, Prepositions, and Word Choice
Articles (a, an, the) seem trivial but test important distinctions. Use "a" before consonant sounds and "an" before vowel sounds: "a unique opportunity" (consonant sound) vs. "an umbrella." Prepositions are notoriously difficult; they often require memorization. Correct: "different from" (not "different than"), "agree with" (not "agree to"), "wait for" (not "wait on"). The ACT includes 2-3 article/preposition questions per test. Word choice questions assess whether you've selected the most precise, contextually appropriate word. Incorrect: "The book's affect on readers was significant." Correct: "The book's effect on readers was significant." Common confusions: affect/effect, their/there/they're, its/it's, who/whom, and to/too/two. Study these homophones and commonly confused pairs intensively. Many test-takers lose points unnecessarily on these straightforward issues. Create flashcards or use interactive platforms like QuizForge (https://ai-mondai.com/en) to drill these distinctions until they become automatic. Your goal is instant recognition, not conscious deliberation during the test.
Strategy: From Rules to Test Success
Knowing 20 grammar rules means nothing if you can't apply them under timed pressure. Develop a systematic approach: first, read each question's underlined portion and the full sentence. Identify what's being tested—is it agreement, punctuation, tense, or word choice? Next, eliminate obviously incorrect answers, then compare remaining choices precisely. Don't rush; approximately 70% of ACT English questions test these fundamental rules, so mastery directly impacts your score. Time management matters: spend no more than 30 seconds per question. If you're stuck, flag it and return later rather than overthinking. Practice with official ACT materials and diagnostic tests to identify your weak areas. Most students struggle with 3-4 specific rule categories; find yours and target intense practice there. Additionally, reading high-quality literature and news sources improves your intuition for correct grammar. Your brain develops pattern recognition that helps you spot errors instinctively. Finally, maintain a personalized error log. When you miss a question, note the rule violated. Review this log weekly to prevent repeating mistakes.
Conclusion: Your Path to 34+
Scoring 34+ on the ACT English section is achievable through systematic mastery of 20 core grammar rules combined with consistent, focused practice. These rules aren't arbitrary; they reflect how educated English speakers communicate. By understanding subject-verb agreement, comma usage, parallelism, verb tense consistency, and word choice nuances, you'll approach the test with confidence and precision. Remember that grammar rules interact; sometimes a single error violates multiple conventions. Comprehensive understanding prevents these cascading mistakes. Start by identifying your personal weak spots through diagnostic testing. Allocate study time proportionally—if you miss 3 out of 4 parallelism questions, spend extra time there. Use interactive tools and flashcards to reinforce learning, and consistently practice with timed sections to build speed without sacrificing accuracy. Your effort compounds; each rule mastered makes subsequent questions easier because you'll recognize patterns faster. With dedicated preparation, you can realistically add 4-5 points to your ACT English score, significantly boosting your composite score and college application competitiveness. Begin today, stay disciplined, and trust the process.
Active recall through practice questions is the fastest way to lock in new knowledge.