I applied through a recruiter. The process took 1 week. I interviewed at Flossmoor Country Club (Flossmoor, IL) in Mar 2012
Interview
There is an open house early in the year, if interested you submit your name and you will receive information about the rules of golf. There is then a 10-15 question quiz on this information that one must pass. Then there is a "skill's assessment" as prospective caddies go out and caddie multiple times for different players that grade them from 0-100. A certain threshold must be met in order to be invited to caddie for the summer.
Interview questions [1]
Question 1
Be sure to know most rules from the rule book, the quiz is not challenging if you review the material at least once over.