SAT Writing & Language: Grammar Rules You Must Know

The SAT Writing & Language section tests a limited set of grammar and style rules repeatedly. Students who struggle with it often do so not because they lack grammar knowledge, but because they don't know which rules are actually tested. This guide covers the high-yield rules that appear most frequently — mastering these alone will significantly raise your score.

1. Subject-Verb Agreement

The SAT loves to separate subjects from their verbs with long intervening phrases, tricking you into matching the verb to the nearest noun instead of the actual subject.

Wrong: "The results of the experiment was inconclusive."
Right: "The results of the experiment were inconclusive."

Rule: ignore everything between the subject and verb. Identify the subject, determine singular or plural, match the verb. Phrases beginning with "of," "with," "along with," "as well as," and "in addition to" do not change the subject's number.

2. Pronoun Agreement and Ambiguity

Pronouns must agree in number with their antecedents, and the antecedent must be clear. The SAT tests both issues.

• Number agreement: "Each student must submit their essay" — "each" is singular, so technically "his or her" is traditional, but the SAT now accepts singular "their." Watch for mismatches like "everyone...they" being marked wrong when context demands a different choice.
• Ambiguous reference: "When Maria met Sarah, she was surprised." Which "she"? SAT will offer an answer that rewrites the sentence to clarify. Always pick the clear version over a pronoun when ambiguity exists.

3. Parallelism

Items in a series or comparison must share the same grammatical form.

Wrong: "She enjoys hiking, to swim, and reading."
Right: "She enjoys hiking, swimming, and reading."

This applies to lists (nouns, gerunds, infinitives — pick one and stick to it), paired constructions ("not only...but also," "both...and," "either...or"), and comparisons ("faster than running" vs. "faster than a run").

4. Comma Rules

The SAT tests four main comma situations:

• Joining independent clauses: Use a comma + coordinating conjunction (FANBOYS). Without the conjunction, use a semicolon. "I studied hard, so I passed" is correct. "I studied hard, I passed" is a comma splice — wrong.
• Non-restrictive clauses: Commas go around information that can be removed without changing the sentence's core meaning. "My brother, who lives in Boston, is visiting" uses commas correctly because "who lives in Boston" is extra info.
• Introductory elements: Comma after introductory phrases. "After studying for hours, she finally understood."
• Do not separate subject from verb: "The tall, experienced professor, teaches physics" — the second comma is wrong because it separates subject from verb.

5. Apostrophes

Apostrophes on the SAT test possession and contraction, and specifically the it's/its and their/there/they're traps.

• its = possessive. it's = "it is"
• their = possessive. they're = "they are." there = location
• whose = possessive. who's = "who is"

6. Misplaced and Dangling Modifiers

A modifier must be placed next to what it modifies. A dangling modifier has no clear referent.

Dangling: "Walking through the park, the trees looked beautiful."
Fixed: "Walking through the park, I saw beautiful trees."

Rule: the subject of the introductory phrase and the subject of the main clause must be the same. If "walking" refers to a person, that person must be the sentence's subject.

Practice Strategy

Grammar rules become automatic through exposure, not memorization. After reviewing each rule, find 10 practice examples. For each SAT Writing question, name the rule being tested before selecting an answer. This metacognitive step accelerates pattern recognition and makes errors obvious rather than ambiguous.