4 Apostrophe Rules: Grammar Guide

by | Feb 28, 2024

4 Apostrophe Rules: Grammar Guide – 

Apostrophes may be small, but they have a big impact on grammar!

Correct usage of the apostrophe shows your reader that you care about the details.  They may seem easy, but there are plenty of places where any of us can have a terrible apostro-fail that downgrades your writing and confuses your readers.

So then, here are the basic do’s and don’ts (or, for followers of The Chicago Manual of Style, dos and don’ts):

DO: Apostrophes for Contractions

Contractions often take a group of words and combine them: They are becomes They’re, She is becomes She’s,  and so on.

Contractions may also shorten a word: Going becomes Goin’, Something becomes Somethin’, etc.  This form of contraction is considered quite informal, and should be used with care.

It is approprate to use apostrophes when forming contractions. One point of confusion related to this is the word It’s. As we would expect, It’s is a contracted form of It is.  However, many people mistakenly use It’s as a possessive:

  • GREAT: It’s my new car. (contracted: it is)
  • APOSTRO-FAIL: Unfortunately, it has a big scratch on it’s hood. (should be: its hood)

As mentioned above, contractions are considered more casual than their full-length counterparts–especially contractions that shorten a word. While they can be an appropriate choice for a variety of situations, formal writing should generally avoid contraction usage.

DO: Apostrophes for Possessive Nouns

Adding -‘s to most singular nouns is the correct way to show a possessive relationship: Tim’s oatmeal cookies, my cat’s water dish.

For plural nouns that end in ‘s’, simply add an apostrophe to show the possessive: workers’ rights, my dogs’ food bowls.

For plural nouns that don’t end in ‘s’, add -‘s: children’s games, mice’s tails.

DON’T: Apostrophes for Possessive Determiners

Words that go in front of a noun to show possession (which are a kind of adjective called Determiners) do not take an apostrophe.  This is straighforward for the majority of determiners, as my, her, his, and our do not appear to need an apostrophe.  As noted above, however, one tricky determiner is its:

  • APOSTRO-FAIL: My car has a scratch on it’s hood. (contracted: it is)
  • APSTRO-FIX: My car has a scratch on its hood. (possessive: its)

Another tricky determiner is your, because it sounds the same as the contraction you’re:

  • APOSTRO-FAIL: You have cat hair on you’re pants. (contracted: you are)
  • APSTRO-FIX: You have cat hair on your pants. (possessive: your)

A similar point of confusion is the determiner their, because it sounds the same as the contraction they’re:

  • APOSTRO-FAIL: They dogs ate all they’re food. (contracted: they are)
  • APSTRO-FIX: The dogs ate all their food. (possessive: their)

The thing to remember is that no pronoun or determiner requires an apostrophe.

DON’T: Apostrophes for Plurals

There are few punctuation mistakes as glaring as the incorrect use of apostrophes to form plural nouns. Consider the following:

  • APOSTRO-FAIL: My two dog’s are named Cassius and Brutus.
  • APSTRO-FIX: My two dogs are named Cassius and Brutus.

Unfortunately, this error is becoming more and more widespread. As a public service to yourself and others, remember that apostrophes don’t make plural nouns. They make possessive nouns, as seen above.

To form a plural for the majority of nouns, add -s or -es with no apostrophe.


Thanks for spending time with this Grammar Guide for Apostrophe Rules!

If you’re interested in learning more, be sure to check out June Casagrande’s The Best Punctuation Book, Period. (available on Amazon)

You might also enjoy Farlex International’s Complete English Punctuation Rules (available on Amazon)


Finally, be sure to check out my Grammar Guide for using Their, There, and They’re correctly


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Mark Pedrin

Mark Pedrin


Mark is an English instructor and communication specialist. He loves helping people develop language skill and insight so that they can reach their personal and professional goals.