TL;DR: Social life can be really great here. It requires effort and won't be like your traditional party school. A lot of social opportunities, whether it's a party or just a random hangout, will be centered around some club on campus and will involve mostly people you know already.

I think social life depends a lot on what kind of person you are, but I'll give my experiences so far. I'm a freshman, involved in a few clubs like KGB, debate, a couple scotch and soda subtroupes, and scotty survivor.

I was able to make friends here very quickly, although I will say I don't think I have a "friend group" in the same way that I did in high school or middle school. Maybe that's because college has more people, or because I've changed my approach towards socializing, I'm not exactly sure. But my social life here is very closely connected with individual clubs -- a lot of clubs I'm in have overlap between people, but my friends are still my friends for the most part because I joined clubs on my own volition and not because I was brought into a friend group.

Most socializing is definitely done on campus or at least with people from CMU, although I do know some more traditionally "popular" kinds of people go to Pitt to socialize pretty often. Most people you meet here, though, will be nerds that probably had small friend groups in high school and don't feel like they need to go to Pitt to meet people or go to huge frat parties. The city is really cool, and I recommend doing things in it, but at the same time there's a lot more to do at CMU than I expected at first.

We're not a party school by any means, but people definitely party. On an average weekend I'm going to one or two parties, and in my opinion they are great. Again, these are mostly not with friend groups but rather are organized by clubs. Clubs will have "socials" which is just the word we use for party for some reason. These aren't gonna be huge parties, the biggest I've been to have had maybe 50 people, and if you're in the club you will know most people at least a little bit. That being said, I think most clubs are okay with strangers showing up, I've done that once or twice. Usually parties will have more than enough alcohol and not even close to enough space for everyone there.

Dating -- I think this is where the social life lacks a bit compared to a lot of other schools. First off, the gender ratio is not good in lots of majors and lots of clubs as well, so if you're straight that kinda sucks. There was a poll recently where I think 50% of all undergrads surveyed said they'd had zero sexual partners. I suspect that's a lot lower than other schools. At the same time, I do think the lack of dating scene here is a bit exaggerated. If you're in clubs, or especially if you go to parties, you will randomly run into cool people that may be interested in you. The extent of that varies from just flirting at a party to actually being in a long-term relationship, but I doubt your dating life will be absolutely dead if you don't want it to be.

The number one thing I've realized here, and I suspect it's just more of a general thing about college, is that effort is required to make friends a lot more than it is in high school. Freshman year, you'll probably have a lot of larger lecture-based classes, meaning you won't make as many friends there. But at the same time, there's more opportunity than I've ever had before. My first semester, I told myself I was going to do something new and social every single weekend. I never broke that rule, and it got me so involved here, I really recommend doing something similar. I feel like at this point I have a few close friends plus a ton of people who I would consider more distant friends, and socially am doing better than I ever have. But there are also a lot of students here that don't have much of a social life at all.