Very casual for a professional interview. Two interviewers alternates in asking questions, one male and one female, which added a good contrast for me. I was sitting sort of between them in a triangle fashion, so I could easily talk directly to each one. The questions were more open concept, which made the interview more of an open discussion between myself and the interviewers. Prior to the interview, the company held an information session to discuss the program for which I was interviewing for. This was also more of a discussion type format which allowed for open questioning and comments about the program.