jp
The competitive eating club is pretty popular. We try to eat as many hot dogs as possible. Of course, only the most popular students can be in this exclusive club. You have to be invited and it is a secret society that will help you throughout life, particularly if you like hot dogs.
Wenzel
Everything is available. There's never a dead moment. At almost any given moment, you can go attend a debate, a play, a dance performance, a fancy dinner party, a frat party, a toasting session, a mixer, an orchestra performance, an a capella performance, or any other bagillion special events that are constantly going on.
Victor
Acapella and theater are huge. For some reason, Yale has the most talented students in arts. Even if you aren't a part of it, it's wonderful to know such talented students and also to benefit from them enjoying their arts.
Also food! It's huge, with amazing dining halls and multitudes of restaurants in New Haven, food is a big one at Yale. Make sure to try New Haven Pizza- amazing.
Jess
You can find a group for pretty much anything, and if you can't, you can start one. (My friends and I founded the Yale Jazzercise Association our freshman year.) Theater, a capella, community service, and publications are big on campus. A fair number of students are involved in Greek life, but frats are a bigger deal than sororities, and most frat parties are open to all students. Other than extracurriculars, though, I'd say residential colleges are a huge aspect of social life on campus, since they determine whom you live with and whom you see most often.
Jess
You can find a group for pretty much anything, and if you can't, you can start one. (My friends and I founded the Yale Jazzercise Association our freshman year.) Theater, a capella, community service, and publications are big on campus. A fair number of students are involved in Greek life, but frats are a bigger deal than sororities, and most frat parties are open to all students. Other than extracurriculars, though, I'd say residential colleges are a huge aspect of social life on campus, since they determine whom you live with and whom you see most often.
Josh
There are hundreds of student groups at Yale, from a capella to sports, politics to religious groups, cultural houses to frats and sororities. It's really hard to say what the most popular groups are, since there are a lot of varying interests at Yale. Socially, though, every weekend there are plenty of things to do--from suite parties to frat parties, dances to student shows and performances. Frats and sororities are not that big here--they're there if you want it, but I know I'm not in a frat and don't feel inhibited at all in terms of my social life. I'm involved in the Yale College Council [Yale's student government], Yale College Democrats, the Office of Sustainability, and various activities within my residential college, Davenport.
Bella
Cultural Houses: I spend a lot of my time at the Asian-American Cultural Center, one of Yale's four (soon to be five) cultural houses on campus. The cultural groups here are great - you don't have to be of a certain racial background to participate in any events hosted by the student groups of each house. For example, I've listened to spoken word at the Af-Am (African-American) House and eaten tamales with my friends at La Casa (Latino House).
The Game: The annual Yale vs. Harvard football game is probably one of the biggest traditions among the undergrads. It's the one event that brings absolutely everyone together in the biggest display of school pride, ever. The bands and half-time shows are great, and the atmosphere is absolutely fun and crazy in the best of ways.
Stay Up Late: Doing homework (lab reports, finishing papers) and just talking to people. Our residential college system is a great way to explore other parts of campus and talk to different groups of people. Student groups and residential colleges also provide study breaks, where you can relax from work and mingle with other people over yummy snacks. Sometimes the best friendships are made when you walk into a common room and just sit down for a two-hour conversation with a then-stranger. The unique stories and experiences of every person on campus are incredible...you just have to take the time to sit down and talk.
Ryan
Everyone seems to be involved in 1-3 extracurriculars, which they love. Each of these extracurriculars either does not affect the rest of their life at all (most publications, community service) or it completely dominates their life (a capella, YPU parties, the YDN). Theatre and a capella are very active, well supported and visible; athletics are less so, but there's a sizeable contingent who's into them. Some people are really into their residential college, but they are usually very boring people. Parties are a big deal; they are very varied and are always happening, at the very least, Thursday-Saturday. Wednesday and Saturday a lot of people go to Toad's, which is this dance club on York St. It's pretty cheesy but a good way to find someone drunk to hook up with. One thing that's nice about New Haven is that the rent is low enough that a lot of people can move off campus and host great parties in off campus apartment; this provides an alternative to the generally subpar frat scene. Luckily though, it's not hard even to throw parties in freshman dorms: alcohol is essential legal on campus for all ages.
Ryan
Extracurriculars are socially mandated at Yale. Everyone is involved in something. Most people will get involved in something political and also something that may be related to their possible future career. Going out on weekends to party is much less ubiquitous - probably 50{4a082faed443b016e84c6ea63012b481c58f64867aa2dc62fff66e22ad7dff6c} or possibly less of the student body does so. This is the largest social divide on campus. Students who go out to frats or Toads will rarely interact with students who don't. Joining a frat definitely isn't a requirement, but it's much bigger than the sorority scene, and they throw lots of parties. In terms of dating, it's true that at Yale, people are either married or hooking up with random people. Either is a respectable option and both are relatively easy to do.
Betsy
Partying is a choice at Yale, which I love. My advice-- find friends who like to party the way you do. There are all types here.