Genitive 's / s'

Also called the possessive case, the genitive case is when we add apostrophe S (’s) to show possession, that something belongs to another or a type of relationship between things.

The Rules:

We normally use the ’s with people, animals though it can also be used with places, organizations and companies (which suggest a group of people).

It is not common to use the ’s with non-living things.

1. Singular nouns

add 's (apostrophe S)

My mother’s house is next to the beach. (= the house of my mother) Jason’s car was stolen last night. (= the car of Jason) Tomorrow, we’re all going to see the museum’s new art exhibit.

2. Plural nouns ending in –s

only add the apostrophe ' (without the S)

The two sisters’ house is next to mine. (= the house of the two sisters) The plumbers’ tools were rusty. (= the tools of the plumbers) The players’ boots were dirty and smelly after the game. (= the boots of the players)

3. Plural nouns not ending in –s:

add 's

Be careful not to trip over the children’s toys. (= the toys of the children) The women’s bathroom is currently flooded with water. The presidential candidate is often called the people’s favorite politician.

4. Singular noun ending in –s:

It depends…

a. Most names: add  's (apostrophe S)

They had a really good time at James’s barbecue last Friday. We spent the day admiring Frances’s new car.

5. Possessive nouns as part of a phrase

Sometimes more than one word/noun is a possessive. The same rules as above are still valid:

The King of Sparta’s wife was called Helen.

I accidentally took someone else’s bag home by mistake.

If there are two owners of something, we add 's to the final name:

Rick and Steve’s car is quite old.

But, if each person owns a car, then add 's to both names:

Rick’s and Steve’s cars are quite old.