My interview process began with telephone screening interviews, the first with an IBM recruiter; the second with a current consultant. Since I've been consulting for a while, the second call was casual and allowed me to ask most of my questions (not all - be thoughtful and professional). From there, I was invited to an interview day at one of several national locations. About 100 candidates were divided into groups of 6-7 and each group was presented a business case. As we worked on the case, interviewers walked around each table to observe how well we interacted, who took the lead, how we resolved issues/differences of opinion, etc. I can't remember now how much time we were allocated to prepare, but each group had to present their findings to a panel. The key throughout is to actively participate, be calm and confident, and think about what you need to say before you get in the room. Don't be shy during the presentation but don't act like Donald Trump either. I've prepped for case study interviews in the past and can say it helped since I don't have a business degree (although I am ABD on a Ph.D.). Now that I've been with IBM over a year, I will say it is extremely important to work as a team during the group presentation. While some candidates will naturally rise to lead the team, everyone has a contribution, and every consultant should strive to be their client's 'trusted advisor.' Good luck!