At Wellesley, if you want to get off campus, and can't drive, you'll end up on a bus. Most students at Wellesley log many hours on both the Senate and Exchange Buses. Many new students head to MIT fraternity parties on the weekends.
Frat parties can be a lot of fun.
It's relatively easy to meet people, the drinks are free, and the music loud. Each fraternity has a different flavor. Some people try them all. But, if you're not interested in meeting lots of inebriated MIT guys, there's still tons of things to do, both on and off campus. It stops at MIT, and is designed for students cross-registering at MIT and Wellesley.