ACT English punctuation rules: commas, semicolons, colons and dashes
ACT English punctuation questions test commas, semicolons, colons, dashes and apostrophes. They belong to Conventions of Standard English, which ACT says is 38–43% of the English section, about 15 to 17 of the 40 scored questions. Most of them come down to one check: can the words on each side of the mark stand alone as a sentence? A semicolon needs a complete sentence on both sides, a colon needs one before it, and a comma alone can't join two.
Where it shows up on the ACT
| Enhanced ACT | |
|---|---|
| Section | English |
| Length | 50 questions (40 scored) in 35 minutes, about 42 seconds each |
| Reporting category | Conventions of Standard English (punctuation is one of its three skill groups) |
| Share of the section | 38–43% of English, about 15–17 of the 40 scored questions |
| In the Composite | Yes. The Composite averages English, Math and Reading. |
ACT publishes the share for the whole category, not for punctuation alone. In the scored English questions of ACT's 2025–26 practice test, we counted 5 punctuation questions (commas, a colon or dash, an apostrophe) and 4 more on sentence boundaries, where the fix is also a punctuation mark. Source: ACT, Preparing for the ACT 2025–2026, pp. 6–10: what each section covers and its reporting categories.
What the questions ask you to do
- Put matching marks around extra information: two commas, two dashes or two parentheses, never one of each.
- Join two complete sentences correctly: a period, a semicolon, or a comma plus and, but, or, nor, for, so or yet.
- Use a colon only after a complete sentence, to introduce a list, an example or an explanation.
- Take out commas that don't belong, such as between a subject and its verb or between a verb and its object.
- Choose the right possessive: city's, cities', its.
The punctuation rules to know
Each row shows a pattern that's correct on the ACT. Compare the answer choices against these.
| Mark | Use it to | Example |
|---|---|---|
| Two commas | Set off information the sentence doesn't need | The founder, a retired captain, donated the books. |
| Comma + and, but, so | Join two complete sentences | The rain stopped, so the game resumed. |
| Comma after an opener | End an introductory phrase or clause | After the storm passed, the crew went back out. |
| No comma | Between a subject and its verb, or a verb and its object | The tall oak by the gate fell in May. |
| Semicolon | Join two closely related complete sentences | The rain stopped; the game resumed. |
| Colon | After a complete sentence, introduce a list or explanation | The kit had three parts: a frame, a lens and a cap. |
| Two dashes | Set off an interruption, like two commas but stronger | The plan—drawn up in 1902—was never built. |
| Apostrophe + s | Show that one owner has something | the city's library, the bus's route |
| s + apostrophe | Show that a plural ending in s owns something | the cities' libraries, the players' bags |
| its / it's | Its = belonging to it. It's = it is or it has. | The bridge lost its paint. It's being repainted. |
Parentheses work like a pair of commas or dashes. The sentence must still be complete if you lift out what's inside.
Common mistakes
Wrong answer choices are often built around these.
- Opening extra information with a comma and closing it with a dash, or not closing it at all. Whatever mark opens the interruption has to close it.
- Joining two complete sentences with a comma alone (a comma splice). "The rain stopped, the game resumed" needs a semicolon, a period or a comma plus so.
- Putting a colon after an incomplete thought. "The kit included: a frame and a lens" is wrong. Drop the colon or finish the sentence before it.
- Adding a comma between a long subject and its verb. In "The tall oak by the north gate, fell in May," the comma has to go.
- Reading only the words next to the blank. Whether a comma is needed often depends on a mark several words earlier.
- Mixing up its and it's. If "it is" or "it has" doesn't fit, the answer is its.
3 example questions with answers
Written by Ashore in the style of the enhanced ACT. They aren't official ACT questions. Try each one before you open the answer.
Question 1 · Easy
The town's first public library opened in 1904. Its founder, a retired ship captain named Elias Ward donated more than two thousand books from his own shelves.
Which choice makes the sentence most grammatically acceptable?
- ANO CHANGE
- Ba retired ship captain named Elias Ward,
- Ca retired ship captain, named Elias Ward
- Da retired ship captain named, Elias Ward,
Show the answer
B. The comma after founder opens the extra description, so a comma has to close it after Ward. Without it, the description runs into the verb donated. Putting a comma before named or before Elias splits the description in the wrong place.
Question 2 · Medium
The museum's newest room is small, but it holds three early inventions the telegraph, the telephone and the radio.
Which choice makes the sentence most grammatically acceptable?
- FNO CHANGE
- Ginventions; the
- Hinventions: the
- Jinventions, such as: the
Show the answer
H. Everything before the blank is a complete sentence, and what follows is a list, so a colon fits. A semicolon needs a complete sentence after it, and the list isn't one. A colon after such as breaks the rule that a colon follows a complete sentence. With no mark at all, the sentence runs together.
Question 3 · Hard
The bridge's first design—drawn by an engineer who had never built a suspension bridge before, was rejected twice before construction began in 1931.
Which choice makes the sentence most grammatically acceptable?
- ANO CHANGE
- B—was
- Cwas
- D; was
Show the answer
B. The interruption starts with a dash after design, so it has to end with a dash before was. A comma there mixes marks. No mark at all leaves the dash unclosed, and a semicolon would cut the subject off from its verb.
More ACT English guides
- Sentence structure
- Grammar and usage rules
- Transitions
- Rhetorical skills
- ACT score calculator: questions right in each section to a 1–36 score and Composite.
- SAT vs ACT: which test fits you better.
- All ACT guides and free tools
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Practice test 1
Example
27
Composite
(28 + 26 + 27) ÷ 3
- English28
- Math26
- Reading27
- ScienceOptional, not in the Composite25