School Ties (1992)
David Green is brought into a prestigious 1950s school to help their football team to beat the school's old rivals. David, however, is from a working class background, so he isn't really "one of them", but he's very successful at making friends. David is a Jew, and has to keep this a secret from his friends for fear of being rejected.
Tagline: Just Because You're Accepted Doesn't Mean You Belong.