ACT English: Introductory Clauses Always Need Commas (Master the Rule)

An introductory clause is any dependent clause that comes before the main (independent) clause. Examples: "When the sun set, the birds flew home." / "Because she studied hard, she passed the test." / "Although it rained, we played outside." In every case, a comma separates the introductory clause from the main clause. If a sentence starts with a dependent clause ending in a verb or action, insert a comma after the clause before the main clause begins. This rule is tested almost every ACT English section.

Quick test: Does the opening phrase or clause contain a subject and verb and cannot stand alone? If yes, it is dependent. Add a comma after it. Example: "After the movie ended we went home" is wrong; "After the movie ended, we went home" is correct.

Example 1: "When students prepare for the ACT, they improve their scores." (Correct: comma after "ACT"). Example 2: "Because the weather was bad, the game was postponed." (Correct: comma after "bad"). Example 3: "Although he was tired, he finished the race." (Correct: comma after "tired"). Example 4: "If you study every day, you will see results." (Correct: comma after "day"). Example 5: "While the presentation continued, the audience listened carefully." (Correct: comma after "continued"). All five follow the same pattern: dependent clause + comma + main clause.

Write these five sentences on a flashcard. Recite the pattern aloud three times daily until it becomes automatic.

Mistake 1: Omitting the comma. "When she arrived she found the house empty" is missing the comma after "arrived." Fix: "When she arrived, she found the house empty." Mistake 2: Using a semicolon instead of a comma. "When the bell rang; students left class" is wrong. A semicolon joins two independent clauses, not an intro clause and a main clause. Fix: "When the bell rang, students left class." Mistake 3: Confusing introductory prepositional phrases (which need commas after 4+ words) with introductory clauses (which always need commas). Remember: if the introductory part has a subject and verb, always use a comma, no matter how short.

During practice tests, mark every sentence starting with a dependent word (when, because, although, after, while, if, since, unless). Check that a comma follows. This habit catches errors fast.

Introductory clause comma errors appear in 3-4 questions per ACT English section (out of 75 questions). That is 3-4 free points if you master this rule. Many students miss them because they do not recognize the clause structure; they hear the sentence aloud and think it sounds okay without the comma. Written English requires the comma even if the sentence sounds fine when spoken.

Dedicate two days to this rule alone. By test day, you should spot introductory clauses instantly and know a comma belongs there without hesitation.