Relative Clause Type #2: Possessive (Whose)

The third type of relative clause begins with the possessive relative pronoun whose for both people and things. You use this form in situations where you have a possessive pronoun:

The company has gone out of business. We bought their parts last year.

• The company whose parts we bought last year has gone out of business.

I'd like to thank John. His help was indispensable in getting this project finished on time.

• I'd like to thank John, whose help was indispensable in getting this project finished on time.

I’d like to thank the members of the public. Their tips were crucial in finding the killer.

• I’d like to thank the members of the public, whose tips were crucial in finding the killer.

Defining/non-defining relative clauses

Just like with Type #1 relative clauses, we have defining and non-defining possessive relative clauses. Compare these two sentences:

1. The customer is really mad. We lost his order.

• The customer whose order we lost is really mad. 

This is a defining possessive relative clause. Because the subject (the customer) is nonspecific, the information in the relative clause is needed to understand who we are talking about. When you read this aloud, there are no pauses.

2. Frank is really mad. We lost his order.

• Frank, whose order we lost, is really mad.

This is a non-defining possessive relative clause. Because the subject (Frank) is specific, the relative clause goes between commas. When you read this aloud, you pause naturally where the commas are.