Most social activities at RPI are Greek-related. Sororities are dry, which means they can't drink in their houses, but this isn't the case at the (off-campus) fraternities. Frats offer the student body a close and safe way to party on the weekends. Fraternity life is not for everyone, and the different fraternities range widely in their interests and specialties. Some men find it hard to get into fraternity parties if they are not Greek-girls are in high demand, but there are already plenty of guys around.
Fraternities are the backbone of the social scene and provide an outlet for students to get out and have a good time. There is no great rift between Greeks and non-Greeks, however. Every Greek organization does a lot of community service, most of which are fun events, and they contribute a lot to the student body and the greater Troy area, as well. Almost every chapter has at least one or two well-known charity events they hold each year. The best advice for incoming freshmen is to go check out as many houses as you can during rush; get to know as many people as you can to find out if there is a Greek organization out there for you. Go to houses with the friends you've made in the dorms, and don't go in with any preconceived ideas. Every house is different, and if you want to go Greek, there's a house for you.