English Experts

OF and ‘S, the Genitive Case

Posted: 24 May 2009 11:00 AM PDT

A common mistake I see with English language learners is the incorrect use of the apostrophe + s, “-‘s” in the genitive case. Although we natives of English use it rampantly, there are moments when it simply cannot be applied. And it is in these moments that I hear my students make mistakes.

Here’s a typical example of how an English learner uses the genitive case incorrectly: the food’s price, the curtain’s color, the book’s title, etc. To the chagrin of the English teacher, the student’s habit of using it this way becomes one quite difficult to break.

There’s much more to this case than meets the eye! Here are a few simple rules to follow:

We normally use -‘s for people, animals, or places:

- Liz’s computer isn’t working.
- Those aren’t my sneakers. They’re my sister’s.
- The dog’s food bowl is empty.
- New York City’s crime rate is at an all time low.

You can use -‘s with time expressions and periods of time:

- Have you seen the headline on the front page of today’s newspaper?
- Santa Barbara is about an hour’s drive from Los Angeles.

Remember that for plural nouns we use s + apostrophe, -s’:

- My brothers’ wives are very nice. (two or more brothers)
- The cats’ toys are in the box. (two or more cats)
- I have three months’ vacation.

For things, ideas etc., we normally use of:

- The price of a university education in The U.S. is extremely high. (NOT the university education’s price)
- The color of his shirt is the same as his shoes. (NOT the shirt’s color)
- The source of her depression comes from a failing marriage. (NOT her depression’s source)

We also say the beginning/middle/end of; the top/bottom of; the front/back/side of:

- I was in the middle of cleaning my house when you called.
- Jim’s house is at the top of the hill.
- Did you see the coat hanger on the back of the door?

Both -‘s and of can be used for an organization:

- The company’s failure was due to overspending. (OR the failure of the company)
- It was the decision of the university Council to fire the professor. (OR the Council’s decision)