Bain first came to recruit through the campus career center. Initial interviews were secured through a preliminary cover letter/resume/transcript drop. About 70 candidates were selected for interviews.
First rounds were conducted on campus, one on one, with two separate interviews of 45 minutes each. Interviews included standard "tell me about yourself" questions mixed in with a case dissection. Interviewers were generally local consultants with Bain & Co, either in their 3 or 4th year with the company. The process itself was very positive: well organized, kept on time, and smartly presented. We were given a folder with a short bio of each interviewer before hand, which was useful in humanizing the interview process.
Second rounds were held at the Boston office. All second round interviewees were flown in. Second round interviews consisted of three one on one interviews of an hour each, in the same format as before. Interviewers this time were two managers and a partner from the office I was interviewing for. By my estimate, another 30 candidates were present at second rounds for my region. Once again, a small folder with pertinent information was handed out. The Boston office's waiting areas was well appointed for the occasion with refreshments laid out for interviewees. That was a nice touch.
In both cases, all travel expenses were reimbursed without question. Bain struck me as very professional and efficient, yet still friendly and welcoming. The interviewers were definitely very poignant but not rude, and were quick to laugh and eager to help. The whole place is pretty much what you'd expect from a company made up of extremely type-A people: efficient, logical, and incredibly driven. Very welcoming if you fit the mold, but it can be intimidating until you understand what it's about.