High school: Not smart enough to fit in with the nerds. Not pretty/outgoing/cruel/vapid/you name it enough to fit in with the cool kids. Definitely not brave enough to fit in with the rebels, though that's where my heart was. I was the new girl in a school where most of the kids had known each other from kindergarten. The new-new girl who showed up a year after me - stunningly gorgeous, exotic, sweet and damaged - became my best friend. (She's still one of my bestest.) My entire class had 35 people. It was a small school. It was daunting to penetrate the formed cliques, so I did not attempt it.
College: I went to a small religious college where many already knew each other because they were from NYC. (I wasn't.) Even though the school was in Israel, anyone not from NYC was considered an "out of towner". I was an outsider. I was not like them. Not as devout, or catty, or rich, or breezily flirty with boys. I didn't have the clothes that were considered in style in that circle (hideously modest). I had friends, mostly out of towners. Which was perfectly fine with me. If you had asked me then, Do you like being an outsider? I'd have said No. But then ask me "Do you want to be an insider?" I'd have said No Way.
Grown Up: I just don't feel like I'm a part of anything. Maybe it's because of the unique school situations. Maybe it's just me.