ACT English: Dashes vs. Commas vs. Colons

An em dash (represented in typed text as two hyphens or a single long dash) is used to insert an emphatic pause or clarification. It interrupts the sentence with extra information and signals that what follows is important or surprising. A dash is stronger and more dramatic than a comma. Compare: "The mayor, a former accountant, proposed a new budget" (comma: neutral insertion) versus "The mayor—a former accountant—proposed a new budget" (dash: emphasizes his background). Both are grammatically correct, but the dash version suggests the background is particularly relevant or unexpected. Dashes also can introduce a list or explanation: "She had one goal for the year—to finish her novel." The dash creates a dramatic pause and highlights what comes next. Use dashes sparingly; overuse makes writing feel choppy and amateurish.

Note: On the ACT, you won't see a literal em dash on the page; instead, you'll see an underlined section asking whether punctuation should be a dash, comma, colon, or something else.

Comma: Inserts a mild interruption or clarification; weakest pause. "The witness, a retired teacher, saw the accident." Colon: Introduces a list, explanation, or second clause that amplifies the first. "She wanted one thing: success." Dash: Emphasizes an interruption or creates dramatic pause; strongest punctuation. "She wanted one thing—success." Rule: If the inserted phrase is essential to the sentence (not a side comment), use no comma. "My sister Jane is a lawyer" (no comma; restricts which sister). If non-essential, use comma or dash. "My sister, Jane, is a lawyer" (comma; there's only one). "My sister—Jane—is a lawyer" (dash; more emphatic). Commas are neutral, dashes are emphatic, colons introduce or explain.

Ask yourself: Am I inserting an extra thought (comma), creating drama (dash), or introducing an explanation (colon)?

Sentence 1: "The committee, composed of five experts, reviewed the proposal." (Correct: comma; non-essential phrase.) Alternative: "The committee—composed of five experts—reviewed the proposal." (Also correct; more emphatic.) Sentence 2: "She had three goals: to travel, to write, and to teach." (Correct: colon; introduces a list.) Wrong: "She had three goals—to travel, to write, and to teach." (Dash before a list is less formal.) Sentence 3: "The results were clear enough to answer the question." vs. "The results were clear—clear enough to answer the question." (Second uses dash to emphasize repetition; both are acceptable depending on intent.) Sentence 4: "He ignored the advice, which proved unwise." (Comma; the which-clause is non-essential.) vs. "He ignored the advice—which proved unwise." (Dash; emphasizes the consequence.) In each case, consider whether you want a mild pause (comma), emphasis (dash), or introduction (colon).

Rewrite the sentences, swapping punctuation, and read aloud. You'll hear the difference in tone.

Punctuation questions on the ACT are often nuanced; the "wrong" choice might be grammatically acceptable but less effective. The test rewards students who understand tone and emphasis, not just rules. These questions appear 2-3 times per section and are worth the same points as easier questions. A student who masters punctuation tone can pick up 3-5 extra points per test.

This week, mark every dash, comma, and colon in a published article or essay. Note the effect of each punctuation choice. Ask: "Why did the writer choose this?" This habit sharpens your ear for punctuation nuance.