ACT English Grammar Rules: The Patterns That Repeat
The ACT English section tests a short, predictable set of grammar rules beyond commas: subject-verb agreement, verb tense, pronoun agreement and case, apostrophes, modifiers, parallel structure, transitions, semicolons versus colons, and wordiness. The test recycles these same patterns every time, so once you can name each one on sight, the section turns into fast, reliable points.
This is the companion to the ACT comma rules guide. Commas carry a big share of the punctuation questions, but the rules below are where the rest of your easy points live. None of this is style-guide trivia. It is a small toolkit you can finish learning in an afternoon. The same conventions appear on the SAT, just packaged differently — see ACT English vs SAT Reading and Writing.
Why this matters on the 2026 enhanced ACT
English is a core section: 50 questions in 35 minutes, about 42 seconds per question, and it counts directly toward your Composite score (the average of English, Math, and Reading). There is no penalty for wrong answers, so never leave a blank. Grammar questions are the fastest points on the test, but only when the rules are automatic. If timing is your real problem, read the ACT pacing strategy guide next. The same grammar control also pays off on the optional essay, so it is worth pairing this with the ACT Writing essay tips.
The pattern set at a glance
| Rule | Test it with | Classic trap |
|---|---|---|
| Subject-verb agreement | Find the real subject, ignore words in between, match the verb. | A phrase between subject and verb that flips the apparent number. |
| Verb-tense consistency | Match the tense of surrounding verbs unless time clearly shifts. | A random tense change with no reason in the sentence. |
| Pronoun agreement and case | Pronoun matches its noun in number; who/whom and I/me by role. | "And I" where the slot needs an object ("and me"). |
| Apostrophes | Possession or contraction only, never to make a plural. | its vs it's; a possessive written as a plural. |
| Modifiers | An opening describer must touch the noun it describes. | A dangling modifier attached to the wrong subject. |
| Parallel structure | Items in a series share the same grammatical form. | Two -ing items and one infinitive in the same list. |
| Transitions | Pick the word that matches the logic between ideas. | "However" used where "therefore" is needed, or vice versa. |
| Semicolons vs colons | Semicolon joins two sentences; colon introduces a list or point. | A colon after an incomplete clause. |
| Wordiness | Shortest grammatically correct choice usually wins. | A bloated answer that repeats an idea already stated. |
Subject-verb agreement: ignore the words in between
The verb must match the real subject in number. The ACT hides the subject by stuffing a phrase between it and the verb, hoping you match the verb to the nearest noun instead.
✓ The box of old photographs sits on the top shelf.
✗ The box of old photographs sit on the top shelf.
The subject is "box," singular, so the verb is "sits." "Of old photographs" is just a prepositional phrase; the plural "photographs" is a decoy. Mentally cross out anything between the subject and the verb, then check the match. Watch for "each," "every," "either," and "neither" too: they are all singular ("Each of the runners is ready").
Verb-tense consistency: do not drift
Keep tenses consistent unless the sentence gives a clear reason to shift in time. A surprise jump from past to present is a classic wrong answer.
✓ She loaded the kiln, set the timer, and waited for the glaze to cure.
✗ She loaded the kiln, set the timer, and waits for the glaze to cure.
The first two verbs are past tense, so the third should be too. The fix is almost always the choice that matches the verbs around it. Only switch tense when the meaning demands it ("By the time we arrived, the show had ended" correctly uses past perfect for the earlier event).
Pronouns: agreement and case
Two separate jobs here. First, a pronoun must agree with the noun it replaces (its antecedent) in number. A singular noun takes a singular pronoun.
✓ Each student turned in his or her form. / All students turned in their forms.
✗ Each student turned in their form. (treated as singular on the ACT)
Second, pronoun case. Use subject pronouns (I, he, she, we, they, who) for the doer and object pronouns (me, him, her, us, them, whom) for the receiver. The "and" construction is the favorite trap.
✓ The coach thanked my teammate and me.
✗ The coach thanked my teammate and I.
Strip out "my teammate and" and you would never say "The coach thanked I." For who vs whom, use the same test: replace with he/him. If "he" fits, use who; if "him" fits, use whom ("the player who scored" = "he scored"; "the player whom we drafted" = "we drafted him").
Apostrophes: possession or contraction, never plurals
Apostrophes do exactly two things: show possession ("the team's bus") or mark a contraction ("don't"). They never make a noun plural. The single most-missed item is its vs it's.
- its = possessive ("the city repaved its roads"). No apostrophe, just like "his" and "hers."
- it's = "it is" or "it has" ("it's raining"). If you cannot expand it to "it is," there is no apostrophe.
- Plural vs possessive: "the Lopez family" becomes plural "the Lopezes," never "the Lopez's."
- Singular vs plural possessive: one dog's leash = "the dog's leash"; many dogs = "the dogs' leashes." The apostrophe sits before the s for one owner, after the s for more than one.
Modifiers: the describer must touch what it describes
An opening descriptive phrase has to modify the noun that comes right after the comma. When it modifies the wrong thing, it "dangles," and the sentence says something absurd.
✗ Sprinting for the train, the doors closed before Daria reached them.
✓ Sprinting for the train, Daria reached the doors just as they closed.
In the wrong version, the doors are sprinting. The fix puts the actual sprinter, Daria, right after the comma. Whenever a sentence opens with an "-ing" or "-ed" phrase and a comma, check that the very next noun is the thing doing the action.
Parallel structure: matching forms in a series
Items joined in a list or by paired conjunctions must share the same grammatical form. Mismatched forms are an easy fix once you spot the odd one out.
✓ The camp offers hiking, swimming, and canoeing.
✗ The camp offers hiking, swimming, and to canoe.
Two "-ing" words and one infinitive break the pattern. Make all three match. The same rule governs paired structures: "not only fast but also accurate," not "not only fast but also accuracy."
Transitions and conjunctive adverbs
Some questions are pure logic: does the sentence add, contrast, or conclude? Pick the transition that fits the relationship between the ideas. "However" signals contrast; "therefore" and "consequently" signal a result; "for example" introduces an illustration.
There is also a punctuation rule baked in. When a conjunctive adverb like however or therefore joins two complete sentences, use a semicolon before it and a comma after it.
✓ The forecast called for rain; however, the sky stayed clear.
✗ The forecast called for rain, however, the sky stayed clear. (comma splice)
Semicolons vs colons
These two get confused constantly, and the ACT offers them side by side to punish a guess.
- Semicolon joins two complete, related sentences, the way a period would: "The lab ran late; we finished the report anyway." A semicolon works only when both sides could stand alone.
- Colon introduces a list or an explanation, and the part before it must be a complete sentence: "Bring three things: a pencil, an ID, and a calculator." Never use a colon after a fragment like "Bring:".
Quick test: a correct semicolon could be swapped for a period. A correct colon could be swapped for "namely" or "here is what I mean."
Wordiness and redundancy: shorter usually wins
A large share of ACT English questions are not about a rule at all. They are about cutting deadweight. When several choices are grammatically correct, the shortest one that keeps the meaning is almost always the answer.
✗ At this point in time, the results were, in fact, completely and entirely unexpected.
✓ The results were unexpected.
Watch for redundant pairs the test loves: "past history," "free gift," "each and every," "small in size," "return back," "final outcome." If a word repeats an idea already present, cut it.
Three tactics that win grammar questions
- Name the rule before you answer. If you can say "this is subject-verb agreement" or "this is a dangling modifier," the right choice usually becomes obvious. If you cannot name a reason for a change, lean toward the shortest clean option.
- Do not fear NO CHANGE. It is correct about a quarter of the time, roughly as often as any other choice. If the original follows the rules and the alternatives only add words, pick it.
- Read past the underline. Agreement, tense, and modifier errors often depend on words outside the underlined part. Read the whole sentence before deciding.
Practice ACT English questions
Four original, ACT-style items. Pick an answer before you open the explanation.
1. The bouquet of bright spring tulips were sitting in the window.
- A. NO CHANGE
- B. was
- C. have been
- D. are
2. My sister taught the new hires and I how to close out the register.
- A. NO CHANGE
- B. myself
- C. me
- D. we
3. The startup moved their headquarters downtown to be closer to its investors.
- A. NO CHANGE
- B. its
- C. it's
- D. they're
4. On weekends the volunteers enjoy planting trees, clearing trails, and they remove litter from the creek.
- A. NO CHANGE
- B. to remove litter
- C. litter is removed
- D. removing litter
Drill it until it is automatic. The app has free ACT English practice questions with instant explanations, plus Math, Reading, and Science sections, a pace timer, and the full technique checklists. Verified against ACT.org.
Start practicing freeFAQ
What grammar does the ACT English section test?
A small, repeating set: subject-verb agreement, verb-tense consistency, pronoun agreement and case, apostrophes, misplaced and dangling modifiers, parallel structure, transitions and conjunctive adverbs, semicolons versus colons, and wordiness. Commas are tested heavily too, covered in the comma rules guide. Learn this pattern set and most questions become quick points.
Is its or it's correct on the ACT?
Use "its" for possession (the dog wagged its tail) and "it's" only when you mean "it is" or "it has." If you cannot expand it to "it is," there is no apostrophe. This single distinction shows up on nearly every ACT English section.
How often is NO CHANGE the right answer on ACT English?
About a quarter of the time, roughly as often as any other choice. Do not avoid it. If the underlined text already follows the rules and the alternatives only add words or errors, pick NO CHANGE and move on. Wondering what score these points add up to? See what counts as a good ACT score.