If you’re a high school student staring down the SAT, you know that the "Reading and Writing" section can be a minefield. But here’s the secret that separates the 1300s from the 1500s: The Writing portion (the grammar questions) is the easiest place to pick up points.
Unlike the Reading section, which requires interpretation, the grammar rules tested on the SAT are finite. They are predictable. They repeat themselves on every single test. By mastering these 10 specific rules, you can walk into the test center with the confidence of knowing exactly what to look for.
This guide is designed for the U.S. student who wants to cut through the noise. Let’s dive into the 10 SAT Grammar Rules that will instantly boost your writing score.
Rule #1: The Apostrophe Showdown: Possession vs. Contraction
This is the lowest of the low-hanging fruit, yet students pick the wrong answer constantly because they rush. The SAT loves to see if you know the difference between "it’s" and "its," or "who’s" and "whose."
Contractions: The apostrophe replaces missing letters.
It’s = It is
Who’s = Who is
They’re = They are
Possession: The apostrophe shows ownership.
Its = Belonging to "it." (Remember, pronouns never take apostrophes for possession. Yours, his, hers, its, ours, theirs).
Whose = Belonging to "whom."
Their = Belonging to "them."
The SAT Trick: They will place "its" and "it’s" in the same paragraph. If you can replace the word with "it is," you need the contraction. If not, you need the possessive.
Example:
The dog chased (its / it’s) tail because (its / it’s) feeling playful.
Answer: its (possession) ... it’s (it is feeling).
Rule #2: Subject-Verb Agreement: Ignore the Distractors
In English, a singular subject needs a singular verb, and a plural subject needs a plural verb. The SAT knows this is easy, so they make it hard by putting a bunch of words between the subject and the verb. This is called a distracting phrase.
The Strategy: When you see an underlined verb, cross out any prepositional phrases (starting with of, in, on, at, to, from, with) or dependent clauses that come between the subject and the verb.
Incorrect (with distractor):
The bouquet of roses from my multiple admirers were sitting on the table.
Analysis: The subject is "bouquet" (singular). The phrase "of roses from my multiple admirers" is just decoration. The verb should be singular.
Correct:
The bouquet... was sitting on the table.
Pro Tip: Watch for "either/or" and "neither/nor." The verb agrees with the subject closest to it.
Neither the teacher nor the students want (plural) to stay late.
Neither the students nor the teacher wants (singular) to stay late.
Rule #3: Pronouns Must Have a Clear Antecedent
A pronoun (he, she, it, they, this, that) replaces a noun. That noun is called the antecedent. On the SAT, if a pronoun is underlined, your first question should be: "What noun is this replacing? Is it obvious?"
The College Board loves to write sentences where the pronoun is vague or ambiguous.
Vague (Wrong):
Maria told her sister that she had won the lottery.
Problem: Who won? Maria or her sister? "She" could refer to either.
Specific (Right):
Maria told her sister that Maria had won the lottery.
(Or restructure the sentence).
The "It" and "They" Trap: Be especially wary of sentences that start with "It" or "They" without a clear referent in the previous sentence.
In the article, it states that the climate is changing.
Wrong. Who is "it"? The article? Just say: The article states...
Rule #4: The Colon and the Dash Are Twins (But Not With Commas)
Punctuation questions make up a huge chunk of the SAT Writing section. The most tested relationship is how to join two independent clauses (complete sentences). However, the colon and dash have a specific function that isn't just about joining sentences.
The Colon (:) : The colon means "Here it comes" or "Pay attention, I'm about to explain or list." What comes before the colon must be a complete sentence. What comes after can be a list, a phrase, or even another complete sentence.
I finally found what I was looking for: my lost keys.
The recipe requires three things: flour, sugar, and eggs.
The Dash (—) : The dash is more flexible and dramatic. It can be used like a colon for emphasis, or it can set off an interruption.
I found what I was looking for—my keys were in the freezer!
The SAT Trap: They will try to trick you by putting a comma where a colon belongs, or by putting a colon in the middle of a sentence where it doesn't belong.
Things I need to buy: milk, eggs, and bread. (Correct)
Things I need to buy, milk, eggs, and bread. (Incorrect)
Rule #5: Commas with FANBOYS (The Comma Splice is Deadly)
You cannot just smack two complete sentences together with a comma. That is called a comma splice, and the SAT penalizes it heavily. To join two independent clauses (sentences that can stand alone), you have two options:
Comma + FANBOYS (Coordinating Conjunction): For, And, Nor, But, Or, Yet, So.
[I wanted to go to the party], but [I had to study for the SAT].
Semicolon (;): The semicolon acts like a "strong comma" or a weak period.
[I wanted to go to the party]; [I had to study for the SAT].
The Rule: If you see a comma joining two complete thoughts without one of the FANBOYS words, it is automatically wrong.
Rule #6: Semicolons are for Best Friends (Related Ideas)
Building on Rule #5, remember that a semicolon is not just a fancy comma. It must have a complete sentence on both sides. However, the SAT also tests the nuance that the two ideas should be closely related.
They will often use a conjunctive adverb (however, moreover, consequently, therefore, furthermore) to create a specific relationship between the two clauses.
The Pattern:
Complete Sentence; however, complete sentence.
Example:
I studied diligently for the exam; however, I still found the grammar section challenging.
Key Rule: Notice the punctuation. It's semicolon, word, comma. Don't let them trick you into using a comma before "however." A comma is too weak to hold those two sentences together.
Rule #7: Modifiers Must Touch the Right Noun
This is one of the most frequently tested "hard" rules. A modifier is a descriptive phrase (often starting with -ing, -ed, or a preposition) that describes a noun. The rule is simple: The modifier should be placed immediately before or after the noun it describes.
If the modifier is separated from its noun, it's called a dangling or misplaced modifier. The result is often hilarious and grammatically incorrect.
Incorrect (Misplaced):
Running for the bus, my backpack fell apart.
Question: Was the backpack running? No. The person was running.
Correct:
Running for the bus, I felt my backpack fall apart.
Incorrect (Dangling):
At the age of six, my grandmother taught me to play piano.
Question: Was your grandmother six years old when she taught you? Probably not.
Correct:
When I was six, my grandmother taught me to play piano.
The Strategy: When a sentence starts with a comma and a descriptive phrase ("-ing" phrase, "-ed" phrase), the very next noun after the comma MUST be the one doing the action of the phrase.
Rule #8: Parallel Structure (The List Rule)
The human brain likes patterns. The SAT knows this, so they break the patterns to see if you notice. Whenever you see a list (of actions, nouns, or adjectives), everything in that list must be in the same grammatical form.
Incorrect:
My hobbies include swimming, biking, and to run.
Analysis: Swimming (gerund), Biking (gerund), To run (infinitive) → They don't match.
Correct:
My hobbies include swimming, biking, and running.
This rule also applies to comparisons.
I would rather go to the movies than to study for the test.
(Keep the "to" consistent).
The "Not only... but also" Trap:
The storm destroyed not only the school but also damaged the church.
Analysis: "Not only" is followed by a noun (the school). "But also" is followed by a verb (damaged). They must match.
Correct:
The storm not only destroyed the school but also damaged the church.
(Verb followed by verb).
Rule #9: Tense Consistency (Logic, Not Habit)
Unlike English class, the SAT isn't trying to trick you on the difference between past perfect and past perfect progressive. They care about logic. Once you establish a time frame (past, present, future), you must stick to it unless there is a logical reason to shift.
Illogical Shift:
We were walking down the street when suddenly a car stops right in front of us.
Problem: The story starts in the past tense ("were walking") and shifts to present tense ("stops"). It should stay in the past.
Correct:
We were walking down the street when suddenly a car stopped right in front of us.
When can you shift?
You can shift to show that one thing happened before another.
By the time the police arrived (past), the car had already driven away (past perfect - earlier past).
Rule #10: Concision (Shorter is Almost Always Better)
This is the final boss of the SAT Writing section. About 20-30% of the questions are simply testing your ability to recognize redundancy and wordiness. The College Board prizes clear, direct writing.
The Rule of Thumb: If you are down to two grammatically correct answer choices, the shorter one—the one that says the same thing with fewer words—is almost always correct.
Redundancy (Common SAT traps):
Wrong: "The reason is because..." (Reason and because mean the same thing).
Right: "The reason is that..." or just "It is because..."
Wrong: "I studied in close proximity to the library."
Right: "I studied near the library."
Wrong: "The two twins were identical in appearance."
Right: "The twins were identical." (If they are twins, there are two. If they are identical, appearance is implied).
The "Ghost" Words: Look for phrases that can be replaced with one word.
"At this point in time" = Now
"Despite the fact that" = Although
"In the event that" = If
Bonus Rule: The Question Mark and Quotation Marks
While not as common, punctuation inside quotes is a frequent flyer on the SAT. In American English (which the SAT uses), commas and periods always go inside the quotation marks. Question marks are trickier: they go inside if the quote is a question, and outside if the whole sentence is a question.
Correct:
"I'm tired," she said.
Did he really say, "I'm tired"?
She asked, "Are you tired?"
How to Apply These Rules on Test Day
Knowing the rules is step one. Applying them under a time limit is step two. Here is your actionable game plan for the SAT Writing and Language Test:
Read the Whole Sentence (or Paragraph): Don't just look at the underlined portion. You need the context to spot modifier errors or pronoun ambiguity.
Identify the "Job": As you read, ask yourself what the question is testing. Is there a comma? (Think FANBOYS or lists). Is there a pronoun? (Think antecedent). Is there a verb? (Think subject-verb agreement).
Predict the Answer: Before looking at the multiple-choice options, see if you can correct the error in your head. This prevents you from being swayed by the tricky wrong answers.
Process of Elimination: Use your rule knowledge to eliminate the "No" answers. If it's a comma splice, cross out any answer with just a comma. If it's wordy, cross out the longest, most awkward ones.
NO CHANGE is Right About 25% of the Time: Don't be afraid to pick "NO CHANGE," but don't default to it. It is statistically correct roughly one out of every four times. If the sentence looks perfect (it has a main verb, a subject, and no punctuation errors), leave it alone.
By mastering these 10 rules, you aren't just improving your SAT score; you are learning to write with the clarity and precision that colleges and future employers demand. Now go crush that test