# Apostrophe rules

Canonical: https://duckyhelper.com/learn/grammar/apostrophes/
Updated: 2026-10-01

Apostrophes do two jobs: they show ownership and they mark missing letters in contractions. For one owner, add 's: the dog's bowl. For a plural owner that ends in s, add only an apostrophe: the dogs' bowls. Plurals that do not own anything take no apostrophe: three dogs. Possessive pronouns like its, yours and theirs never take one, and it's always means it is or it has.

## The rules

| Rule | Wrong | Right | Why |
| --- | --- | --- | --- |
| One owner: add 's | *the girls backpack* (one girl) | *the girl's backpack* | One girl owns it. |
| Plural owner ending in s: add ' | *the girl's backpacks* (many girls) | *the girls' backpacks* | The plural is *girls*; add just an apostrophe to show they own them. |
| Plural not ending in s: add 's | *the childrens' toys* | *the children's toys* | The plural is *children*, so add 's. |
| Plain plurals: no apostrophe | *We bought three pizza's.* | *We bought three pizzas.* | Nothing is owned. It is just more than one. |
| Contractions: apostrophe replaces letters | *Theyre late.* | *They're late.* | *They're* = *they are*. The apostrophe stands where the *a* was. |
| Possessive pronouns: no apostrophe | *The team won it's game. Is this your's?* | *The team won its game. Is this yours?* | *His, hers, its, ours, yours, theirs* already show ownership. |

## Two owners

If two people own one thing together, put the apostrophe on the last name only: *Ana and Leo's robot* (one robot, built together). If each owns their own, put it on both: *Ana's and Leo's phones* (two phones).

> **Note: Names that end in s**
>
> Style guides differ. Chicago, MLA and APA write *James's book* and *Chris's car*. AP style, used by many newspapers, writes *James' book*. Both are seen in print; pick the style your class uses and be consistent. Plural family names follow the plural rule: *the Joneses' house*.

## Worked examples

**Example 1: one owner or many?**

Problem: *My three ___ leashes hang by the door.* (dog / dogs / dog's / dogs')

1. How many dogs? Three. So start with the plural: *dogs*.
2. Do they own something? Yes, the leashes. So show ownership.
3. The plural ends in *s*, so add only an apostrophe.

Answer: *My three dogs' leashes hang by the door.*

**Example 2: find the apostrophe mistakes**

Problem: *The Smith's dog lost it's collar, so the kid's next door made poster's.*

1. *The Smith's dog*: the dog belongs to the Smith family, a plural owner. The plural is *Smiths*, so write *the Smiths' dog*.
2. *it's collar*: the collar belongs to it, so use *its*. Test: *it is collar* makes no sense.
3. *kid's* and *poster's* do not own anything here. They are plain plurals: *kids*, *posters*.

Answer: *The Smiths' dog lost its collar, so the kids next door made posters.*

## Common mistakes and fixes

| Mistake | Fix |
| --- | --- |
| Adding 's to make a plural (*apple's for sale*) | Plurals take no apostrophe: *apples for sale*. |
| Writing *it's* for ownership | Say *it is*. If it sounds wrong, use [its](https://duckyhelper.com/learn/grammar/its-vs-its/). |
| Putting the apostrophe in the wrong place for plural owners | Write the plural first (*students*), then add the apostrophe (*students'*). |
| Writing decades with an apostrophe (*the 1990's*) | Most styles write *the 1990s*. Use *'90s* only when letters are left out. |

## Practice

**Five apostrophe questions**

1. We have three dogs. Which word fits? *The ___ leashes were hanging by the door.*
   A. dogs'
   B. dogs
   C. dog's
   D. dogs's

   Answer: dogs'. There are three dogs, and they own the leashes. The plural *dogs* ends in *s*, so add only an apostrophe. *Dog's* means one dog, *dogs* shows no ownership, and *dogs's* is not a standard form.

2. Which word fits? *The ___ toys were all over the floor.*
   A. childrens'
   B. childs'
   C. childrens
   D. children's

   Answer: children's. *Children* is already plural and does not end in *s*, so add 's. *Childrens* is not a word, and *childs'* uses the wrong plural.

3. Which sentence uses apostrophes correctly?
   A. We bought three pizza's.
   B. The cat licked it's paw.
   C. My sister's backpack is blue.
   D. The Smith's live next door.

   Answer: My sister's backpack is blue.. One sister owns the backpack, so *sister's* is right. *Pizzas* and *the Smiths* are plain plurals with no ownership, and the cat's paw needs *its*.

4. Which word fits? *___ going to be late if we do not leave now.*
   A. They're
   B. There
   C. Their
   D. Theyre

   Answer: They're. The sentence means *They are going to be late*, so use the contraction *they're*. *Their* shows ownership, *there* is a place, and *theyre* is missing its apostrophe.

5. Ana and Leo built one robot together. Which phrase is correct?
   A. Ana's and Leo's robot
   B. Ana and Leo's robot
   C. Anas and Leos robot
   D. Ana and Leos' robot

   Answer: Ana and Leo's robot. For one thing owned together, the apostrophe goes on the second name only. Apostrophes on both names mean each person owns a separate one, which does not match one robot. *Anas and Leos* drops the apostrophes, and *Leos'* would mean an owner named Leos.

## Frequently asked questions

### Is it James' or James's?

Both appear, depending on style. Chicago, MLA and APA add 's (*James's*). AP style adds only the apostrophe (*James'*). In school writing that follows MLA or APA, *James's* is the expected form. Whichever you use, use it every time.

### Do you use an apostrophe for plural letters and numbers?

Usually not for numbers: *the 1990s*, *in her 20s*. For single lowercase letters, many styles do use one so they are readable: *mind your p's and q's*. Check your style guide if it matters for an assignment.

### Why does its not have an apostrophe if it shows ownership?

Because it is a possessive pronoun, like *his* and *hers*, which never take apostrophes. The form *it's* was already taken by the contraction for *it is*. If you would not write *hi's*, do not write *it's* for ownership.

## Sources

- [Purdue OWL, Apostrophe Introduction](https://owl.purdue.edu/owl/general_writing/punctuation/apostrophe_introduction.html), accessed 2026-10-01
- [Purdue OWL, Quotation Marks and Apostrophes](https://owl.purdue.edu/owl/multilingual/multilingual_students/punctuation/quotation_marks_and_apostrophes.html), accessed 2026-10-01

## Related

- [Its vs it's](https://duckyhelper.com/learn/grammar/its-vs-its/)
- [Capitalization rules](https://duckyhelper.com/learn/grammar/capitalization/)
- [SAT grammar: Form, Structure, and Sense](https://duckyhelper.com/learn/sat-reading-writing/form-structure-and-sense/)
- [Grammar study guides](https://duckyhelper.com/learn/grammar/)

## Try asking Ducky

- "Find every apostrophe in my essay and ask me whether each one shows ownership or a contraction."
- "Is it students' or student's in this sentence? Help me figure it out."
- "Quiz me on plural possessives until I get five right."

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