Larry Kroger (Tom Hulce) and Kent Dorfman (Stephen Furst) are freshman in college in 1962 and want to join a fraternity. After visiting several, including the snobby Omega house, they come to the Delta house pledge party. Here they meet handsome, compulsive womanizer Otter (Tim Matheson), his adventurous best friend Boone (Peter Reigert), Boone's girlfriend Katy (Karen Allen), the daring thrill-seeker D-Day, the responsible Hoover, and the unforgettable Bluto. They are accepted into the fraternity and join in on the wild toga parties, road trips, and pratical jokes. But Dean Wormer is determined to have Delta kicked off campus and its members expelled, so he enlists the help of Omega house and its leaders Doug Neidermyer and Greg Marmalard and new pledge Chip Diller (Kevin Bacon). Yet, Delta won't go away quietly.