I applied through the career office and got a phone interview with a recruiter. It was a short 15 minutes interview to basically narrow down the candidates. When they were down to about 3-5, they put all of us for a real 30 minute interview with two Directors in the Group where I was supposed to work in over the summer. Because of my college's location, all interviews were done on the phone, so I guess that made it easier. Basically it was all fit/personality, with (if I remember correctly) NO technical questions asked (that could also be attributed to my liberal arts/economics background). TIAA CREF is a very nice guy place, so as long as you are an interesting person, humble and willing to learn, you should be fine at the intern level.