I applied through my school Career Center and, despite huge competition, got the interview. I signed up as the first interviewee of the day which I only learned afterwards could have been a mistake. The 1 on 1 interview was very behavioral, with "why finance?" as the toughest question. We walked through my resume, explaining different experiences and how they relate to what's going on at BlackRock. My interviewer was extremely polite and seemed very happy to work at the company herself - this whole thing might have deceived my senses and perception a little bit.