What question would tell you where someone's heart is?
edw519: "Is there a single question..."No.  And there shouldn't be.Instead of spending time and energy trying to determine the perfect quesiton, why don't you just spend that same time and energy actually talking to people.Talk about anything.  Listen as much as you talk.  "Engage" them.  After 5 minutes of sincere (this is key!) interaction and a half dozen subjects, you'll probably have a pretty good idea of where their heart is.A low tech solution that has been working very well forever.  All it takes is a little practice.OTOH, if you don't do this and probe with a single question, you'll look phony and won't learn anything.