ACT English Grammar: Top Tested Rules for 2026

More than half of the ACT English questions on recent tests hit on just a few core grammar and punctuation rules. This means practicing smarter, not just harder, can really boost your score. The ACT English section has 75 questions to answer in 45 minutes. That's not just about knowing grammar; it's about being quick. Roughly 40% of the section drills punctuation, 30% tests grammar and usage, and another 30% looks at sentence structure and rhetorical skills. You'll definitely see your score go up by zeroing in on these common errors.

Punctuation Rules: Where to Focus

About three-quarters of all punctuation questions deal with commas, apostrophes, and dashes/colons. If you ignore these, you're making a big mistake.

Commas: Your Biggest Challenge

Commas pop up more than any other punctuation mark. You'll get questions about introductory elements, non-essential clauses, lists, and separating independent clauses with a coordinating conjunction. If two independent clauses are joined by and, but, or, nor, for, yet, or so, you have to put a comma before the conjunction. Also, if an introductory phrase has three or more words, it almost always needs a comma. Shorter ones? The comma is often optional, but read the sentence carefully.

• Introductory elements: Use them to separate clauses or phrases that start a sentence (e.g., "After the rain stopped, the sun emerged.")
• Non-essential clauses/phrases: Use them to set off info you could remove without changing the sentence's main point (e.g., "My brother, who lives in London, is visiting.")
• Lists/series: Separate three or more items (e.g., "apples, oranges, and bananas"). The ACT usually likes the Oxford comma (the one before the 'and').
• Compound sentences: Put a comma before a coordinating conjunction that connects two independent clauses (e.g., "She studied diligently, and she aced the exam.")

Apostrophes: Possession and Contractions

Apostrophes show possession or form contractions. Mixing up its (possessive) and it's (it is) is a classic ACT trap. You also need to know the difference between plural possessives like students' (many students have something) and singular possessives like student's (one student has something). You'll typically see 2-3 apostrophe questions per test, often mixed in with comma questions.

Dashes and Colons: Less Common, Still Important

Dashes and colons don't show up as often as commas, but they're still crucial. A dash can signal a sudden change in thought or set off an emphatic, non-essential clause, basically acting like a really strong comma. A colon introduces a list, an explanation, or an elaboration, but it must come after a complete sentence. You won't use a colon after an incomplete thought or a verb.

"Many students confuse semicolons and commas. Semicolons link two independent clauses, while commas can't do that on their own without a coordinating conjunction." - PrepGuin Grammar Handbook, 2026 Edition.

Grammar and Usage: Frequent Mistakes

Subject-verb agreement and pronoun agreement/case are always big point-getters. Expect several questions on each.

Subject-Verb Agreement: Matching Numbers

A verb always has to match its subject in number. Sounds easy, right? But the ACT makes it tricky by putting stuff between the subject and verb. Watch out for prepositional phrases, subordinate clauses, or phrases like along with, as well as, or in addition to. These don't change what the subject is. For example, in "The group of students is studying," group is singular, so the verb is is singular.

• Collective nouns: Think of them as singular unless the sentence really emphasizes the individual members (e.g., the team is, the committee votes).
• Indefinite pronouns: Each, every, neither, either, anyone, everyone, no one, somebody, something are always singular. Always.
• Compound subjects: If they're joined by and, they're usually plural. If joined by or or nor, the verb agrees with the subject closest to it.

Pronoun Agreement and Case: Be Clear and Consistent

Pronouns have to match their antecedents in number and gender. If the antecedent is singular, the pronoun has to be singular (e.g., "Each student must bring his or her own laptop."). To avoid gender bias, use plural forms if possible, or his or her. Pronoun case (subjective I, he, she, we, they vs. objective me, him, her, us, them) also gets tested, especially in comparisons or with compound subjects/objects. A quick trick: take out the other person from the compound to see which pronoun sounds right (e.g., "He and I went" vs. "She invited him and me").

Modifiers: Put Them in the Right Spot

Dangling and misplaced modifiers make sentences awkward and confusing. A modifier should sit as close as possible to the word or phrase it describes. To answer these questions correctly, just make sure things are clear. "Running quickly, the bus was missed by the student" doesn't make sense; the bus isn't running quickly. It should be "Running quickly, the student missed the bus."

Sentence Structure and Rhetorical Skills

The ACT also tests if you can write clear, concise sentences and make good rhetorical choices. This often means consistent verb tense, no redundancy, and good organization.

Verb Tense: Keep it Consistent

Verb tenses should stay the same throughout a passage unless there's a strong reason for a time shift. Look for small changes in sentences or paragraphs that mess up the flow. If a story is in the past tense, don't suddenly switch to the present unless it's a direct quote or a general truth. Had been means something happened before another past event.

Redundancy and Wordiness: Get to the Point

The ACT loves concise writing. If two choices mean the same thing, or if you can say something in fewer words without losing meaning, the shorter option is almost always the right one. This often means cutting unnecessary adverbs, repeated ideas, or extra prepositions. Watch out for phrases like basic fundamentals (that's redundant) or returns back (wordy).

Here's a rough breakdown of how questions are distributed, based on ACT, Inc. analyses and official tests from the 2026-26 school year:

Skill Category	Approximate % of Questions
Punctuation (Commas, 's, :- )	40%
Grammar & Usage (S-V, Pro-Ante)	30%
Sentence Structure (Modifiers, Tense)	15%
Strategy (Clarity, Conciseness)	10%
Organization (Paragraph, Passage)	5%

Style and Strategy: Choosing the Best Answer

Some questions ask you to pick the answer that best achieves a specific goal, like keeping the flow going, providing a transition, or making things clearer. These are rhetorical questions. You need to understand the passage's overall meaning and what it's trying to do. The correct answer usually fits right in and improves the argument or description. Transition words are big here; they connect ideas logically.

What to do this week

• Go over comma rules, especially for introductory elements and non-essential clauses.
• Practice telling the difference between its and it's, and getting singular/plural possessives right.
• Do a timed English section from an official ACT practice test. While you're working, try to identify the question types.
• Use PrepGuin's Adaptive Drills feature. You can specifically target punctuation and subject-verb agreement questions. This will help you pinpoint your weak spots and fix them fast.

If you can nail the most common ACT English grammar rules, your score will go up. PrepGuin's Guided Roadmap gives you a clear path, helping you focus on these high-yield areas with targeted practice and detailed explanations for every question. And our Mistake Vault means you'll keep seeing your past errors until you've truly got them down.