ACT English: Commas Before Conjunctions in Compound Sentences—FANBOYS

A compound sentence joins two independent clauses with a coordinating conjunction (FANBOYS: for, and, nor, but, or, yet, so). Rule: Independent clause + comma + conjunction + independent clause. Example: "I studied hard, and I passed the exam." (Two clauses: "I studied hard" and "I passed the exam," joined by "and" with comma.) The comma MUST go before the conjunction when joining two independent clauses. Without the comma, it is a comma splice (if comma alone) or run-on (if no comma). Without a conjunction, it is a semicolon sentence.

Note: Commas don't go before "and" in compound objects or verbs. "I studied hard and passed the exam" (no comma—only one clause). Comma only when two full independent clauses meet.

For (because—less common): "He left, for he was tired." And (addition): "She ran quickly, and he followed." Nor (neither—pairs with "neither"): "Neither option worked, nor did a third." But (contrast): "The plan seemed good, but it failed." Or (choice): "We can go now, or we can wait." Yet (contrast—similar to "but"): "It was late, yet they continued." So (result/cause): "The weather was bad, so we stayed home." Each conjunction has a different meaning; choose based on the relationship between clauses. For test purposes, the most common are and, but, or, so, and yet.

Always use a comma before these conjunctions when joining independent clauses.

Sentence 1: "I like pizza, and my friend prefers pasta." Correct. Two independent clauses + comma + "and." Sentence 2: "She studied hard but still failed the test." Correct if "still failed the test" is an independent clause. Check: "Still failed the test" is not a complete clause (no subject). So NO comma is needed: "She studied hard but still failed the test." Sentence 3: "The party was fun, so we stayed late." Correct. Two independent clauses + comma + "so." Before adding comma+conjunction, verify you have TWO independent clauses, not one clause with a compound predicate.

Build this habit: see conjunction, ask "Are there two independent clauses?" If yes, comma before conjunction. If no, no comma.

Compound sentence comma-conjunction errors appear in 2-3 ACT English questions per section. Mastering this rule eliminates a high-frequency error source and yields 1-2 guaranteed points.

Learn the rule once: independent clause + comma + FANBOYS + independent clause. By test day, you will instantly spot and fix this error.