In my school, there isn't a 'popular' group. People who try their hardest to fit in only TRULY classify other students in groups. Keep this in mind, whenever you be yourself, people of your same personality would be-friend you, and you'll have your own little group.
Example: In my science class I had before June 3rd, you had different 'types' of students. In one area, we had boys who were funny played sports, got girls, and dressed nicely. Because they all had the same personality type, they made good friends. (Most people would call this type the popular group.) Also, in that same group, we had the students who did drugs and student that were gang-bangers. They were just like the 'popular' ones, but they just skipped class, and never played sports.
Behind them, you had the types who were more devoted to doing the work and passing the class. They didn't really talk to the other students much and they were pretty much the opposite than the other group, but they all got along well. They helped the 'popular' ones with the work, and they'd laugh and talk too, but quietly. (People would call them nerds.) Basically, it really didn't seem like a group to me. It was mixed.
Almost all of us girls got along.
Finally, there were three students that sat alone, not doing any work. They seemed like the Columbine, Virginia Tech types. They skipped class, and always got into trouble. They were similar to the gang members, but they were solo. (People didn't have a name for them, but I made sure I stayed the hell away from them.)
I say, whenever people get accepted into a certain 'group,' they take part in what they have in common. The popular ones play sports, and get the girls together, the nerdy ones do work together, and the crazy ones plot to shoot up the school together. However, of you're a girl and you get accepted into the group I hang with, then you're going to be beautiful, and you would LOVE to shop. We're glamorous girls.