Jake
The biggest group on campus is by far the Hillel. Many students are involved in fraternities or student government or the student newspapers. For the past few semesters student life on Penn's campus has exploded with the introduction of many new choral groups.
Gionni
There are so many groups on campus. It's overwhelming how many options a person has. I've been involved a lot with the Latino community on campus. La Casa Latina is a cultural center for the Latino kids on campus. It's great because it creates a sense of community and introduces us to one another. Through La Casa, I joined the Mentorship Pathways Program which paired me with a senior English major. We went to several programs about resumes, maximizing study times, bowling, and a play. It was great.
I also joined the Penn Latin and Ballroom Dance team. I had so much fun on the team. I learned Cha-cha, Rumba, Waltz, Tango, Foxtrot, Samba, and others. It was a lot of fun. I plan on joining Onda Latina in the future. It's a dance team that performs as a show.
Luis
The most popular organization would have to be the Undergraduate Assembly. A group that I am involved with is the Society for Pre-Law Students of Color. We are hosting a conference next week (see tinyurl.com/RPAC2012 for more details). Students do not leave dorms open, typically. There are horror stories of thefts and no one wants to risk something being stolen. In smaller dorms, however, the culture may be a little different depending on the level of trust among hall mates. There is really good security everywhere as well. Athletic events are pretty popular, and there are a select few games that are promoted heavily, with free tickets given out on Locust Walk. Guest speakers come all the time, and shows presenting comedians and other artists are regularly planned as well. The dating scene is what you make of it. There are plenty of fish in the sea. I met my closest friends during my first year and continue to make friends now. when you live with a person you really get to know them. If I am awake at 2 AM on a Tuesday I am probably doing work that I procrastinated on. As with any college, people party all the time, but the majority of parties happen on the weekends. Fraternities and sororities are not that important. Only about 30{4a082faed443b016e84c6ea63012b481c58f64867aa2dc62fff66e22ad7dff6c} of the students here go greek, so don't feel any pressure to do so. Last weekend, I spent time with my girlfriend and went to North Philly to eat at an authentic Puerto Rican restaurant. You can do so much on a Saturday night that doesn't involve drinking: you can go to the Rave theater on 40th and Walnut, go out to dinner or bowling in Center City, or plan a trip to Penn's Landing to catch some fireworks. There is a lot of exploring to do. I live off campus so I have become a member of the greater Philadelphia community.
Kate
A few popular groups are Mask and Wig, the Excelano Project, International Affairs Association, and the Penn Democrats. Mask and Wig is a all-male performing arts group that is highly talented and selective. The members must be proficient in singing, comedy, dancing, and writing sketches, and they mount a completely original production every year and tour the country performing it over Spring Break. The Excelano Project is a spoken word/poetry group that is open to participants and proves perennially popular. The International Affairs Association is the equivalent of Model UN, and is the biggest group on campus. The Penn Democrats is another large organization that is dedicated to politics from a democratic perspective. The members volunteer, hold events, and bring speakers to campus, and currently are a key part of the youth reelection campaign for the President.
Depending on the dorm, people will leave doors open and be very neighborly. The Quad dormitory and Hill dormitory are best for that atmosphere, as the three high-rise dorms offer more amenities but a diminished social aspect. Many upperclassman live off-campus, and situations there vary widely. Most people make lasting friendships from their dorms and New Student Orientation, but many are also formed during traditions like Homecoming. Athletic events are not hugely popular, but big events like games against Princeton will attract more of a crowd. For most students, the highlight of the Penn social scene is the April Spring Fling festival that takes place right before final exams. A full weekend event with a concert and carnival, Spring Fling is the biggest party on the East Coast and offers entertainment from fried Oreos to bouncy castles. The party (and hook-up) scene is strong at Penn, but not everyone chooses to partake. Frats host parties very often during the year, enough so it is rare that NO parties (near campus or downtown in clubs) are slated for a particular day. The Greeks are the biggest throwers of parties, but not the only ones. You are always able to find something to do, whether it is going to a friend's performance, a muscial in central Philly, a frat party, or a movie with friends.
Kaytlena
One popular student group is SPEC, which brings celebrities to Penn. Every year, they have famous speakers come in (recently, James Franco, Bill Cosby, and Joseph Gordon-Levitt). They also organize Spring Fling, which is one massive party for a whole weekend in April. There's a carnival in the Quad with music and food, and then there's a concert one night with people like Flo Rida, Akon, and Kid Cudi. People from all over come to Penn during that weekend. But Penn has a large umbrella of student groups on campus, and you'll most likely be able to find one that suits your interests. And if not, it's really easy to start one of your own. I started a group called the UPenn China Care Club, which raises money for orphans in China with medical disabilities, and also provides a mentorship program for children in Philadelphia who have been adopted from China. It was easy to register the club, and easy to recruit students!
The social life at Penn is known to be relatively better than at other Ivies, because it has lots of nearby bars and clubs, making it easy to find something to do on weekend nights. And getting downtown is not hard either. Philadelphia has a ton of great restaurants, and going to BYOs is definitely a popular activity among Penn students. I don't think there's really a drinking stereotype, because you can find students at both ends of the spectrum. There are some who never drink, and some who are at a bar more days of the week than they aren't. It all depends on your preferences.
Unfortunately, athletic events aren't too popular because the sports teams aren't that great, but football games are fun to go to nonetheless. It's also pretty easy to get involved with the club/intramural sports teams.
Andi
Penn's large size means that just about everyone finds a group of friends easily. Many people become close with the friends they make in the dorms during the first weeks of school Freshman year, and those who don't like their hall-mates will meet their social group through extra-curriculars and student clubs. The trick is that you have to seek these groups out, and be willing to spend time at Hillel, the Writer's House, the Newman Center, or whatever extra-curricular "second home" interests you.
There are plenty of students at Penn who don't drink alcohol, but people who are offended by the thought or sight of people who drink might feel uncomfortable living on campus.
Jesse
There are certain freshman dorms that create social barriers of sorts. The Quad and Hill are by far the best places to live. If you don't live there, it feels harder to meet people and get involved. The social scenes in dorms like Kings Court and Stouffer tend to be very different from the Quad and Hill.
I am in a fraternity, so much of my social life revolves around that. About a third of students at Penn are involved in Greek life, but it is not the only possibility. While there are other parties on campus, fraternity parties tend to dominate the scene. There are also a few bars on campus that are frequented by Penn students.
Off-campus there a ton of possibilities. There is a very lively nightlife/bar scene for the 21 and over crowd. The Phillies, 76ers, and Flyers are all only a short subway ride away. Philly is also full of amazing restaurants, particularly BYOs, which allow you to bring beer or wine in to the restaurant and tend not to card.
Mark
The social life in Philadelphia is great. There are plenty of parties, performances, etc. on campus, and even more a short bus ride away. Philadelphia is incredibly central to many places such as New York and Washington DC, making weekend trips there very common.
With 10,000 undergraduates, political activism is definitely present and active, but usually within a small percentage of those undergraduates. Like most campuses, there are significant numbers of liberals and conservatives; however, unlike most campuses, people everywhere on the political spectrum are respected for their opinion.
Lisa
While it's nice to study in Van Pelt for hrs and hrs, Philadelphia is always a short cab ride away. The little restaurants, the night life(21 or not:)!),the culture,the sports,theaters, shops...Forget Boston, Philly's the quintessential college city!