Together with Harvard, the toughest MBA program to get into in the world. Wharton will not look at you unless you have 4+ years of quality business experience - which sucks if you are on the young side trying to get in there, but good once you get in, as you will be surrounded for the most part by serious students. The curriculum has the reputation of being brutally quantitative - but your hard work will pay off with a great job come graduation.