The 12 SAT Grammar Rules you need to know

If you’re taking the digital SAT, you should know that the Reading and Writing section tests grammar concepts extensively. Without mastering the SAT Grammar Rules, it’s basically impossible to lock in a top SAT Reading and Writing score. 

The worst part is that many students don’t learn these grammar rules in school! Instead, most students rely on what “sounds right” or “looks right.” But that’s a sure way to get yourself in trouble and lose points on the digital SAT. 

At PrepMaven, we’ve got decades of experience coaching students to top SAT scores, and we’ve used that experience to put together this guide on every grammar concept tested on the digital SAT. If you can master every grammar concept in this blog post, you’ll be in a great spot to earn a high SAT Reading and Writing score!

If you’re looking to work with a professional SAT tutor, check out our expert review of the 15 Best Online SAT Tutoring Services!

Jump to section:
Overview: how is grammar on the SAT Reading and Writing?
SAT Grammar Rules: Punctuation
SAT Grammar Rules: Verbs
SAT Grammar Rules: Pronouns
SAT Grammar Rules: Sentence Construction 
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The digital SAT (2024 and on) no longer separates Reading and Writing into two different sections. Instead, both concepts will be tested in the same section. For our guide on the “Reading” half of the Digital SATs Reading and Writing section, check out our post here. According to College Board, roughly 26% of the questions on the SAT Reading and Writing section test “Standard English Conventions.” In other words: over a quarter of your digital SAT Reading and Writing questions are on grammar!

Below, we’ll break down each of the grammar concepts tested, and explain what you need to know to approach it. If you want an overview of how the SAT is structured, check out our post on the SAT sections here, and if you want an overview of all the content tested on the SAT, check out our guide here

The most important grammar rules you can learn for the digital SAT’s Reading and Writing section are about punctuation. We can’t stress this enough: if you use our grammar tips to master the SAT punctuation rules, you’ll see your Reading and Writing score jump almost immediately. 

So, what do you need to know about punctuation on the digital SAT? Well, it’s all about clauses! There are a finite number of grammar rules that determine what kind of punctuation you can use, and these rules depend on what kind of things the punctuation is separating. 

So, before you can charge headlong into the fray of SAT grammar questions, you need to know the difference between Complete and Incomplete sentences. This grammar concept is so crucial, we’ve actually got a whole post on it right here. For now, a quick summary: 

  1. A complete sentence (also known as an Independent Clause) is simply something that could stand on its own as a sentence within a longer piece of writing. It has a subject, a verb, and it’ll make sense as a complete idea if you put a period after it. 
  2. An Incomplete Sentence is, well, just something that cannot be a sentence on its own. If you put a period after it, it would not express a complete thought. 

That’s the short version: check out the blog post for more information and examples! For now, read on to learn the most important punctuation rules you need to know. 

SAT Punctuation Rule 1: A semicolon separates two complete sentences

This one is easy! In almost every instance, the semicolon is exactly the same as a period. If you have a complete sentence before it and a complete sentence after it, then the semicolon is always correct! 

If, on the other hand, the semicolon is between a complete sentence and incomplete sentence, it is wrong. All you have to do is check what’s on either side of the semicolon, and you’ll be on your way to getting the question right. 

Note: there is one super rare exception. It almost never comes up on the SAT, but we want to be thorough, so we’ll explain it here. If you have a really long, complex list within a sentence, you can use semicolons to separate the items in the list (the same way you’d normally use commas). Take a look at the example below, but remember–this grammar rule almost never comes up on the SAT Reading and Writing section!

Before getting home, I needed to pick up my dog’s medicine and drop him off at the vet; swing by the store to pick up milk, eggs, and bread; and fill up my car at the gas station.

It’s a neat exception to know, but focus on the fact that in 99% of cases on the digital SAT, the semicolon separates two complete sentences. 

SAT Punctuation Rule 2: A comma cannot separate two complete sentences. 

If you can master this SAT grammar rule, you’ll be able to eliminate tons of wrong answer options! And this one is quite straightforward, with no pesky exceptions: a comma can never separate two complete sentences. 

It’s as simple as that! Technically, this is called a “comma splice,” but all that matters is your ability to recognize it when it happens. If you know you’re dealing with an SAT punctuation question and you see a comma in your answer option, the very first thing to do is to check whether it’s separating two complete sentences. If so, it’s wrong!

SAT Punctuation Rule 3: A comma with a FANBOYS separates two complete sentences

Depending on your past English teachers, you may have just done a double take: fanboys? When it comes to SAT grammar rules, FANBOYS is an acronym for the seven coordinating conjunctions: 








FANBOYS! Don’t get hung up on the grammar terms here: all you need to know is that if you have a comma and one of these seven words, you need to be combining two complete sentences. Take a look at some right and wrong examples below: 

Example 1: I like cats, and I like dogs. [Correct!]

Here, the two complete sentences are linked with a comma and a FANBOYS (“and”), so this works grammatically! 

Note: if you just had “I like cats, I like dogs,” that would be wrong! Remember: a comma by itself can’t connect two complete sentences. 

Example 2: I don’t know if we should go to the movies, or go to the mall. [Wrong!]

Even though this example might look okay, it’s wrong. Not just that: it’s a classic kind of wrong answer option you’ll see on the SAT Reading and Writing. The rule for Comma + FANBOYS is that they connect two complete sentences. In our example, the first half is a complete sentence, but the second half is just “go to the mall,” which, in this case, is not a complete sentence. 

So, the correct version of this sentence would not have the comma: “I don’t know if we should go to the movies or go to the mall.” would be correct!

Incorporating this rule into your SAT grammar strategy is absolutely critical, and will save you tons of points on the SAT Reading and Writing section!

SAT Punctuation Rule 4: Colons follow a complete sentence

Many students find colons confusing, but they’re really not so bad. The most important colon rule for the digital SAT is that the colon can only come after a complete sentence. 

What about what comes after the colon? Well, this can be either a complete sentence or an incomplete sentence! What it must do, however, is explain something that the stuff before the colon leaves unanswered. Think of it as completing a piece of the puzzle: the colon tells you that whatever comes after it will help explain whatever came before it. 

Take a look at a classic example below: 

There was only one problem with our experiment: we forgot to collect any data! 

Why does the colon work here? The first thing to check is whether it comes after a complete sentence, and it does. The second thing is to see whether the stuff after the colon helps “complete the puzzle,” which it also does: it explains the “one problem” with the experiment. 

That’s pretty much all you need to know about colon rules for the Digital SAT Reading and Writing section!

SAT Punctuation rule 5: dashes signal an interruption in a complete sentence

Dashes: what are they good for? It’s another tricky piece of punctuation, but we’ll break down the only two ways that dashes get used on the digital SAT, and you’ll have these mastered in no time. 

The easiest way to think about dashes is as a signal that we’re interrupting a complete sentence–almost like we’re changing direction. There are two ways this can happen. If you have a full complete sentence, and then want to add something else on at the end, you simply use one dash to introduce that new information. 

In this case, all you need to do to check if the dash is correct is to make sure that it follows a complete sentence

The more common way the SAT tests dashes, however, is when they introduce an interruption into the middle of a complete sentence. In this case, they work exactly like parentheses. If you use two dashes, then you should be able to remove everything between the dashes and be left with a complete sentence that still makes sense. 

Take a look at this example: 

I picked up everything–the food, the drinks, and the games–at 9 am this morning so that we’d be ready for the party tonight!

See how those dashes could be replaced with parentheses? And how, if you took out the stuff between the dashes, the sentence would still be complete and make sense? That’s all!

SAT Reading and Writing strategy tip: If you see a dash as an answer option on the digital SAT, your first move should be to see if there’s another dash already in the sentence that needs its twin!

On the digital SAT Reading and Writing section, there are two key Grammar rules when it comes to verbs. Although the rules themselves may seem simple, developing a strong SAT grammar strategy will depend on really mastering the nuances of these grammar rules!

SAT Verb Rule #1: Verb tense must remain consistent

Verb tense refers to the ‘time zone’ of a verb, indicating when this action, occurrence, or state of being is happening.

In general, the tense of the verb in question must match the tense of the surrounding context.

The surrounding context might mean the sentence itself. It could also mean a part of a sentence or the paragraph as a whole. This is why it is so important to read carefully for context when encountering any Verb question on SAT Reading and Writing!

So, if a sentence begins with the phrase “In 1989,” we can assume that the tense of that sentence will be in the past. If a paragraph is discussing an ongoing condition, such as “modern businesses’ efforts to maximize workplace efficiency,” we can assume that the tense of this paragraph will be, for the most part, in the present.

The key is to mine your context for clues that indicate what the tense standard is, and then ensure that your answer choice matches that tense. Here are some examples of common verb tense “clues” on SAT Reading and Writing:

  • Another verb in that tense in context (i.e., “studied,” “will walk,” or “breathes”)
  • A time clue (i.e., “In 1989,” “last year,” or “in the coming decade”)
  • A transition word or phrase (i.e., “meanwhile,” “lastly,” or “at first”)

SAT Verb Rule #2: Verbs must match their subjects

This is the heart of subject-verb agreement: verbs must match their subjects! (Remember: a “subject” in grammar is simply what/who is doing the verb.)

But what do we mean by “match”? All this means is that plural subjects take one form of the verb, while singular subjects take a different form. It’s so simple, you do it every time you speak without even thinking about it: would you say “He walk to the store” or “He walks to the store?” That, at its heart, is all that subject verb agreement is about. 

Here’s what that generally breaks down to:

  • A plural noun must have a plural verb
  • A singular noun must have a singular verb

A plural noun is a noun that indicates more than one of some thing, idea, or individual: horses, children, mosses. A singular noun indicates that there is only one of some thing, idea, or individual: horse, child, moss.

Now, even though we don’t always think of verbs in terms of their singularity or plurality, a verb will change form depending on whether its noun is plural or singular. Take a look at the following examples to see this in action:

  • The horses run across the field.
  • The horse runs across the field.
  • These mosses are hard to identify.
  • This moss is hard to identify.

In the first two examples, the plural noun (horses) matches the plural verb (run), while the singular noun (horse) matches the singular verb (runs). Run and runs are different verb forms.

In the second two examples, the plural noun (mosses) matches the plural verb (are), while the singular noun (moss) matches the singular verb (is). Are and is are different verb forms.

Now, our ears are pretty good at “hearing” when subject-verb agreement is off. Notice, for example, how “wrong” these phrases sound when you read them out loud or in your head:

  • Horses runs across the field.
  • The moss stick to the tree.
  • Mary deliver the book to her friend.
  • Cross-contamination are common.

These all sound “wrong” to our ears because the agreement is incorrect. You can apply the same test to verb and subject combinations on the digital SAT, and eliminate those that clearly don’t sound “right.”

SAT Reading and Writing strategy tip: The digital SAT loves to cram in a bunch of words between a subject and its verb to confuse students. That’s why it’s so essential to practice identifying a sentence’s subject and its associated verb correctly, which we discuss in our Verbs blog post

Even advanced students get tripped up by the harder versions of these questions, which is why we strongly recommend putting in at least a few sessions with an expert PrepMaven SAT grammar coach: they won’t just teach you the concepts, they’ll help you develop an SAT grammar strategy that saves you precious points on these tricky questions. 

For more practice with digital SAT punctuation, download our free diagnostic quiz below!

Just like with verbs, there are two pronoun rules tested by the digital SAT Reading and Writing section. The first one is going to look a lot like the last rule we covered: 

SAT Pronoun Rule 1: Pronouns must match their antecedents 

Sorry for using the annoyingly complicated grammar word there: an “antecedent” is just whatever the pronoun is referring back to. Pronouns always replace nouns, so “the antecedent” is just whatever noun the pronoun refers back to. For example, in the sentence “The business saw its profits plummet,” we know that the “it” refers back to “the business.” 

The main thing that the digital SAT tests when it comes to pronouns is whether they agree in number with their antecedents. It’s just like with verbs: a plural antecedent needs a plural pronoun, and a single antecedent needs a singular pronoun. 

Any time you see a pronoun on the SAT, identify what specific noun it’s replacing/referring to. If that noun is plural, your pronoun must be plural as well. If it’s singular, then the pronoun ought to be singular. 

Remember: “it” is always singular, and “their” is always plural on the SAT Reading and Writing. 

SAT Pronoun Rule 2: Pronouns must be unambiguous

This rule is one that people often forget, but it’s crucial. Within any given sentence, a pronoun must clearly refer to only one known. In other words, it shouldn’t be possible to read a pronoun as referring to multiple different things. Take a look at an example of this rule being broken: 

 The scientists tried to stay thorough while collecting data points on the test subjects, but they ended up lost. 

The pronoun is “they,” right? But who/what is the “they” here? We know that it probably refers back to the scientists, but it isn’t actually clear because we have multiple plural nouns in the sentence that “they” could refer back to. “They” could be the scientists, sure, but “they” could also be the data points or the test subjects!

In a case like this, the digital SAT will always offer you an answer option that makes the pronoun more specific or replaces it entirely. One solution to the above example might simply be: “The scientists tried to stay through while collecting data points on the test subjects, but the data ended up lost.”

SAT Reading and Writing strategy tip: as soon as you see a pronoun in the question, identify exactly what noun it’s referring back to or replacing! Use this free diagnostic worksheet to see if you know what you need to about pronouns!

There are a few grammar rules that many people don’t even realize the digital SAT tests, and most of these have to do with specific issues of sentence structure. While these rules are tested less frequently, they are still tested on almost every test at least once!

SAT Sentence Structure Rule 1: Modifiers must be placed correctly

A “modifier” refers to a word or group of words that provide more information about a certain subject. In most Modifier questions on the SAT or ACT, a modifier is a descriptive phrase that provides additional details about a subject, often appearing at the start of a sentence.

Here are some examples of modifying phrases that might offer further details about a specific subject:

walking down the street

bespectacled and grimacing

associated with ancient tradition

In general, modifiers and modifying phrases must be right next to whatever it is they are modifying! Take a look at these sample sentences that use the modifying phrases above:

Walking down the street, my friend and I took in the gorgeous sunset.

Bespectacled and grimacing, the professor made his way to the lectern.

Associated with ancient tradition, the practice of ancestral worship appears in many cultures.

In all of these examples, the modifying phrases are placed directly next to the subject they are modifying. Misplaced modifiers are called “dangling modifiers,” and these incorrectly modify a subject. Here are the same examples written with dangling modifiers:

My friend and I took in the gorgeous sunset, walking down the street. 

The professor made his way to the lectern, bespectacled and grimacing.

The practice of ancestral worship appears in many cultures, associated with ancient tradition.

Technically, due to the misplaced modifiers, these sentences declare that it is the sunset that is “walking down the street,” the lectern that is “bespectacled and grimacing,” and the cultures that are “associated with ancient tradition.” 

In reality, we know that the sentences want to say that the friends are walking down the street, the professor is bespectacled and grimacing, and the practice of ancestral worship is associated with ancient tradition. But we need to make sure that the modifiers are closest to whatever they’re meant to modify–otherwise, we get those wrong “dangling modifiers.” 

These questions don’t appear often, but knowing this grammar rule can help you lock in an extra question or two on the digital SAT Reading and Writing section!

SAT Sentence Structure Rule 2: Items in lists must be parallel

Parallelism isn’t just a concept that appears in math. It also concerns grammatical structure, especially with respect to comparisons or lists.

To apply parallel structure, ensure that items in a comparison or list are in the same form, category, and/or number. 

In this next example, the verbs in the list all have the same form (-ing):

Desmond spends his days at the library photocopying, transcribing, and cataloging articles.

Here, the nouns in the list are all singular, reflecting parallelism in number:

Someday I hope to invest in a car, a retirement account, and a rental property.

All that parallel structure really means is that all of the things in your list share the same general form. If one thing in your list is a noun, the other things should be nouns as well. If one thing is an “ing” verb, all the other things should be as well. 

SAT Reading and Writing Strategy Tip: if you see that a digital SAT question asks you about one part of a list, simply look at the other parts of the list and change it to match. 

SAT Sentence Structure Rule 3: Comparisons must be logical

This one might sound funny: what’s it mean for a comparison to be logical? In a nutshell, all this means on the SAT Reading and Writing section is that you if you’re making a comparison, you must be comparing the same category of thing.

It sounds obvious, but it can actually sneak by us in writing. Take a look at this relatively easy example: 

The price of burgers has gone up way more than fries. 

Can you spot why that comparison is illogical? Technically, it’s comparing “the price of burgers” to just “fries” themselves, which doesn’t make sense (what would it even mean for “fries” to go “up?”). 

These can be tricky to spot, but they’re usually pretty easy to fix. The digital SAT will usually have you fix these by adding in a pronoun like “these” or “that.” Take a look at how we can use those to fix the previous example: 

The price of burgers has gone up way more than that of fries.

Notice the difference? By introducing the pronoun “that,” we’re now really saying that the price of burgers has gone up way more than the [the price of] fries! Look out for these on the digital SAT: they’re sneaky questions. But the answer options are the biggest clue: if you see that your answer options contain the phrases “those of” or “that of,” it’s a good bet that the question is testing logical comparisons!

These SAT grammar rules will help you approach all of the grammar questions on the Reading and Writing section. But don’t forget about the other question types! To familiarize yourself with the other concepts tested on the digital SAT Reading and Writing section, check out our post on What’s on the SAT.

In the meantime, if you’re serious about developing a strategy to maximize your digital SAT Reading and Writing score, you’ll want to use these grammar rules in conjunction with an understanding of the new digital SAT’s format. Check our post on everything you need to know about the digital SAT and how to prepare for the new digital SAT, and start prepping!

If you’re looking for more personalized help, you can get paired with one of our expert tutors, each of whom has experience guiding students through all of the SAT grammar concepts. 

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Mike is a PhD candidate studying English literature at Duke University. Mike is an expert test prep tutor (SAT/ACT/LSAT) and college essay consultant. Nearly all of Mike’s SAT/ACT students score in the top 5% of test takers; many even score above 1500 on the SAT. His college essay students routinely earn admission into their top-choice schools, including Harvard, Brown, and Dartmouth. And his LSAT students have been accepted In into the top law schools in the country, including Harvard, Yale, and Columbia Law.