Applied through on-campus recruiting at top-10 university. Process took a little over 2 weeks. First round interviews were on-campus and consisted of two 45-minute interviews with Project Leaders. Both spent 5-10 minute upfront on behavioral questions before jumping into cases. BCG cases are very candidate-led, so having a strong structure upfront is key to being able to crack the cases. I made my way through both first round cases pretty quickly, which gave me lots of time to just chat with my interviewers and ask them questions at the end of each interview. I received a call the day after my interview informing me I had made it to the second round in my preferred office. One of my interviewers also called before my second round to give me interview feedback and also told me that BCG decision round interviews place a very strong emphasis on fit with the firm. Second round interviews were on-site at the BCG office. My decision round interviews were the same format as my first round (two 45-minute interviews--apparently format can vary between each office though) and were with partners in the office. In my experience, my interviewers in the second round spent a lot more time casually chatting/asking fit questions than my first round interviewers. The cases were also lot less structured than the ones I saw in the first round, with partners often deviating from calculations, etc to ask me to brainstorm ideas. I received a call later that day from one of the partners who interviewed me and was extended an offer.