At Adams College, the jocks rule the school from their house on high, the Alpha Beta fraternity. So when a group of socially-challenged misfits try to go Greek, they're instantly rejected by every house on campus. Deciding to start their own fraternity to protect their outcast brothers, the campus nerds soon find themselves in a battle royale as the Alpha Betas try to crush their new rivals.

The nerds are now in control of the university, as a result of Lewis Skolnick and the rest's actions in the two previous movies. A new generation of sportsmen arrive, however, determined on winning the school back. The principle, himself an ex-nerd fighter, helps them, and the nerds return to suppression. Harold Skolnick needs help from his uncle Lewis, the hero of the first two movies. Lewis, however, are not too proud of his nerd past, and won't reveal any of it, much less help his nephew. However, his wife makes him change his mind, and with help from his friends from the first two movies, they start the fight to win the school back, using classic nerd tricks.

Lewis and his nerdy friends attend Booger's wedding to the daughter of a rich politician, but nerd-haters in the family do everything possible to prevent the wedding going ahead. Meanwhile, Lewis awaits with eagerness the birth of his unborn foetal child...

The members of the Lambda Lambda Lambda fraternity travel to Fort Lauderdale for a fraternity conference. They'll have to beat off the attacks of their rival frat, the Alphas, if they want to maintain their self-respect -- and, of course, if they want to get anywhere with the pretty girls!