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SAT Apostrophe Rules: Its vs It's, Plural Possessives, and the Expansion Test

Updated July 7, 2026

What are the SAT apostrophe rules?

You keep losing points to the same handful of apostrophe swaps: its vs it's, their vs they're, and figuring out where the apostrophe lands when more than one thing owns something. Here is the whole thing: an apostrophe does exactly two jobs, it marks a contraction (letters left out) or it marks possession on a noun, and possessive pronouns never take one. The rest of this page is the single test that tells you which job you are looking at, every time.

The Expansion Test

An apostrophe question is really a fork in the road: contraction or possession. The Expansion Test picks the road for you. Take the word in question and stretch it back into the two full words a contraction would stand for. If the sentence still makes sense expanded, it is a contraction and the apostrophe stays. If the expansion turns into nonsense, you wanted the possessive, and the possessive pronoun gets no apostrophe at all.

Watch it run on the classic:

The committee revised it's / its recommendation.

Expand "it's" to "it is": "The committee revised it is recommendation." That is garbage, so this is not a contraction. The word means "belonging to it," so it is the possessive its, no apostrophe.

Now the mirror case:

It's / Its been a long application season.

Expand it: "It has been a long application season." That works cleanly, so it is a contraction, and it's is correct. One note that saves you: it's can expand to either "it is" or "it has." Try both. If either lands, the apostrophe belongs.

The test is boring on purpose. You do not sound it out, you do not go by feel. You expand, you read, you decide. Grammar the SAT tests rewards this kind of mechanical checking, the same way the four core grammar rules reward it over instinct.

Its/it's, their/they're, whose/who's

Every homophone pair the SAT loves is the same fork wearing a different costume. The contraction expands. The possessive does not.

  • it's = it is / it has. its = belonging to it.
  • they're = they are. their = belonging to them. (And there = a place or "there is," which is neither.)
  • who's = who is / who has. whose = belonging to whom.
  • you're = you are. your = belonging to you.

Run the same move on each. "The debate team lost their / they're funding" expands to "they are funding," which breaks, so it is the possessive their. "Whose / Who's presenting first?" expands to "Who is presenting first?", which works, so it is the contraction who's. You do not need to memorize four separate rules. You need one test and the discipline to run it on the word actually printed in front of you.

Singular vs plural possessive (s' vs 's)

Once you know a word is possessive, a second question appears: where does the apostrophe go, before the s or after it? That depends on one thing only, whether the owner is singular or plural.

  • Singular owner: add 's. The senator's staff. One senator.
  • Plural owner already ending in s: add just the apostrophe, s'. The senators' staff. Many senators.
  • Irregular plural not ending in s: treat it like a singular and add 's. The children's museum, the women's team, the people's vote. There is no such word as "childrens'."

The apostrophe placement is not the hard part. The hard part is that the SAT often hides the owner count in the passage and makes you find it. "The scientist's data" and "the scientists' data" are both spelled correctly. Only the surrounding sentence tells you whether one researcher or a whole lab is doing the owning. So before you place the apostrophe, answer the real question the test is asking: how many owners does the passage establish? Then the placement is automatic.

Nouns vs pronouns (why "its" has no apostrophe)

Here is the root of the its/it's confusion, and fixing it fixes half your apostrophe misses. Possessive nouns take an apostrophe (the dog's leash, the teachers' lounge). Possessive pronouns do not. Its, hers, ours, yours, theirs, whose: every one is already possessive by itself, and adding an apostrophe to any of them is always wrong.

Students trip because the two systems disagree. Your ear learns "possession means add an apostrophe-s" from nouns, then wrongly exports that rule to pronouns. It does not carry over. The pronoun already did the job internally. This is the same "match the exact word, not the nearby pattern" habit that pronoun agreement questions reward, and it is worth building deliberately.

And the plainest rule of all, the one the other three rest on: a simple plural never takes an apostrophe. Two dogs, three essays, the 1990s, several PDFs. If the word is just naming more than one thing and owning nothing, no apostrophe touches it. Ever.

Traps to name before they cost you points

The SAT engineers apostrophe wrong answers to survive a quick glance. Name the patterns so they stop working on you.

  • The plural-that-looks-possessive. "The colleges' brochures" is right if many colleges own brochures, but "the college's mascot changed over the decades" needs no apostrophe on "decades," because decades own nothing there. Apostrophe questions and plain-plural questions get stacked in the same sentence on purpose.
  • The decade and acronym trap. "The 2000's" and "three CD's" are both wrong. Plurals of numbers and letters take a bare s: the 2000s, three CDs.
  • its' is not a word. There is no configuration where "its" takes an apostrophe after the s. If you see it in a choice, eliminate it on sight.
  • The ear trap. Read aloud, its and it's are identical, their and they're are identical. Your ear cannot break the tie, which is exactly why the test uses these. Reading it aloud is not a check here. Expanding it is. Trusting your ear here is a small behavioral leak: a habit that costs points independent of what you know.

The drill: run the three-question check on your own test

Do this today with your most recent practice section. For every word that ends in -s or sits next to an apostrophe in the answer choices, run three questions in order:

  1. Is this just a plural (more than one, owning nothing)? Then no apostrophe.
  2. Does it show ownership? Then find where the owner ends, and put the apostrophe there ('s for one, s' for many).
  3. Can I expand it into two words that still make sense? Then it is a contraction, and the apostrophe stays.

Exactly one answer should fit the sentence's real meaning. If you catch yourself picking by which version "looks normal," that is the leak, and the three questions are the fix. Score the section twice if you want proof: once on gut, once on the checklist. The checklist wins, and the gap between the two scores is the number of points this one page is worth to you.

Practice it now: the free simplesat grammar drill runs live apostrophe items with per-trap feedback, so you can build the Expansion Test into reflex against real question shapes. No signup, works as a guest.

Frequently asked questions

Is it "kids'" or "kid's"?

It depends entirely on how many kids. One kid owning something takes kid's (the kid's backpack). Two or more kids owning something takes kids' (the kids' playground). The word is spelled correctly both ways, so the passage has to tell you the number. Find the owner count first, place the apostrophe second.

Do possessive pronouns ever take an apostrophe?

No, never. Its, hers, ours, yours, theirs, and whose are already possessive on their own, and adding an apostrophe to any of them is always wrong on the SAT. An apostrophe on one of those words (it's, who's, they're) can only be a contraction, so if the sentence does not mean "it is," "who is," or "they are," the apostrophe version is wrong.

How common are apostrophe questions on the test?

They live inside Standard English Conventions, which is about a quarter of the Reading and Writing section, so they appear regularly rather than constantly. That is good news: they are rule-based and fast to fix, which makes them some of the cheapest points to recover. Learn the one test here and you close the whole category, the same way subject-verb agreement closes with one mechanical move.

What does "it's" actually stand for?

It expands to either "it is" or "it has," and nothing else. If neither expansion fits the sentence, you do not want "it's," you want the possessive "its" with no apostrophe. Always try both expansions before deciding, because "it's" hiding a "has" ("it's been slow") is the version students overcorrect and get wrong.

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