Two interviews. One with faculty (which seemed as much an information session as anything else) and one with the admissions committee member (which was more structured, and the one which the interviewer is in charge of bringing up your name at the admission's comittee meeting). Both overall were quite casual. I happened to have a resume with me, the interviewers liked this (and was helpful to me becuase it was closed file). Also, if you have good scores, mention them during the interview (it will make the interview easier). Most importantly, the food for lunch was very good (I especially liked the sweet tea).