It's perfectly valid English. "Who're" is a contraction of "who are"†. However, for some reason, unlike more common contractions, it is much more common in spo

It's perfectly valid English. "Who're" is a contraction of "who are"†. However, for some reason, unlike more common contractions, it is much more common in spoken English than in written. †http://dictionary.reference.com/browse/who're http://dictionary.reference.com/browse/who're