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ACT · English

ACT English grammar rules cheat sheet

22 rules across 5 groups: the punctuation, agreement, modifier, concision and rhetoric rules behind the ACT English section's 75 questions. Each rule is one line, with the error to spot and the fix.

Practise them in the ACT English drills — mechanics, punctuation and rhetoric, each with a worked explanation after every question.

Grammar rules by topic

Punctuation

Comma splice (wrong)
two complete sentences joined by only a comma
Fix: period or semicolon
I ran. I was late. / I ran; I was late.
Fix: comma + FANBOYS
I ran, but I was late. (for/and/nor/but/or/yet/so)
Semicolon
joins two independent clauses with no conjunction
Colon
introduces a list or explanation after a complete sentence
Non-essential clause
set off with a pair of commas (or dashes) on both sides
Apostrophe — possession
singular: the dog's leash; plural: the dogs' leash
Apostrophe — contraction
it's = it is; its = possessive, never a contraction

Subject-verb & pronoun agreement

Subject-verb agreement
the verb agrees with the subject, not a word next to it
Collective nouns
team, group, committee — usually singular ('the team is')
Pronoun agreement
a pronoun matches its antecedent in number ('everyone... their' → informal; 'everyone... his or her' → formal)
Ambiguous pronoun
flag it if the pronoun could refer to more than one noun

Modifiers

Dangling modifier
the opening phrase must describe the very next noun
Misplaced modifier
put a modifying phrase next to the thing it actually modifies
Parallel structure
items in a list or comparison share the same grammatical form

Word choice & concision

Redundancy
cut words that repeat an idea already stated ('past history', 'each individual')
Wordiness
the shortest option that preserves meaning is usually correct
Commonly confused words
affect (verb) vs. effect (noun); its vs. it's; their/there/they're
Transition words
however/moreover = contrast/addition; therefore/thus = consequence

Rhetorical skills

Adding a sentence
ask whether it supports the paragraph's main point — relevance beats interest
Sentence placement
look for the pronoun/transition that only makes sense after a specific sentence
Tone consistency
match the passage's existing register — formal stays formal throughout

The free full-length ACT practice test reports English by topic and by pace, so you can see whether a rule is costing you points or just time.

Take the free practice testMath formula sheet

ACT English questions, answered

What does the ACT English section test?

Seventy-five questions in 45 minutes, split between Conventions of Standard English — punctuation, sentence structure, agreement, modifiers — and the rhetorical skills of organisation, concision, tone and whether a sentence belongs in its paragraph. About half the questions are pure grammar; the rest ask you to judge writing rather than fix it.

Which grammar rules come up most on the ACT?

Commas, by a wide margin: setting off non-essential clauses, the comma splice, and the absence of a comma between a subject and its verb. Then apostrophes, subject-verb agreement across an interrupting phrase, and the semicolon. On the rhetoric side, concision (the shortest correct option is usually right) and transition words appear in every passage.

Is ACT English grammar the same as SAT grammar?

The rules are the same; the format is not. The ACT embeds them in five long passages and moves at 36 seconds a question, so you need to recognise a rule on sight. The SAT gives one short passage per question and more time. This sheet is shared between the two.

How do I practise ACT English?

Under a clock. Take the free full-length ACT practice test and check the English breakdown by topic and pace, then work the three English drills in the question bank — mechanics, punctuation, and rhetoric — which explain every answer. A rule you know but apply slowly needs repetition, not a lesson.