The words whose and who's are homophones. Although they sound alike and both are related to the pronounwho, they have different functions.

Definitions

Whose is the possessive form of the pronoun who (as in "Whose books are these?").

Who's is the contraction of who is (as in "Who's coming with me?").

Also see the usage notes below.

Examples

• Whose turn is it to drive? Who's driving tomorrow?
• "When a man tells you that he got rich through hard work, ask him: 'Whose?'"
  (Don Marquis)
   

• "A parade is an extraordinary spectacle whose whole purpose is to display itself."
  (Margaret Visser, The Way We Are. HarperCollins, 1994)
• "The enemy is anybody who's going to get you killed, no matter which side he's on."
  (Joseph Heller)

Usage Notes

• "This one is quite hard to forgive as it's so easy to check: just replace whose or who's by the full-length version, i.e. 'who is.' If this make sense in the context, then you can use who's if you wish. If it doesn't make sense, then the right spelling is whose."
  (Philip Gooden, Who's Whose: A No-Nonsense Guide to Easily Confused Words. Walker & Company, 2004)
• "Contrary to certain opinions, there is no difficulty at all in using whose with reference to things. It is perfectly normal in standard English to write sentences like the following: The plane, whose pilot had safely ejected, crashed into the woods . . .. Of course, you should always consider whether the alternative of which might give you a more elegant result."
  (R.L. Trask, Mind the Gaffe! Harper, 2006)

Practice

(a) _____ car was damaged?

(b) _____ going to pay for repairs?

(c) "Fen gazed at her with something of the triumphant and sentimental pride of a dog owner _____ pet has succeeded in balancing a biscuit on its nose."
(Edmund Crispin, The Case of the Gilded Fly, 1944)

Answers to Practice Exercises

Glossary of Usage: Index of Commonly Confused Words