In Nelsonville, Ohio in 1956, nonconformist, extroverted Eugene "Gene" Harbrough moves from Chicago, living next door to the introverted, clumsy Jonathan Bellah. They soon develop a friendship, with Gene deciding to take him under his wing and teach him how to attract women.

Jonathan's main objective is to win over the sexy Marilyn McCauley, in spite of his shyness. Gene proclaims that he can guide him to win her over in a month.

Gene has his own love life to maintain with his crush, Bunny Miller, who reciprocates his feelings. He also defends Jonathan and himself from the wealthy class bully, Kenny, Bunny's jealous jock boyfriend.

After a confrontation at the drive-in, Kenny challenges Gene to a game with their cars, center line chicken. Neither backs down in time, so both cars are damaged. Gene's father hits him for damaging the car and grounds him. This shows the dysfunctional relationship he has with his widowed father, who has zero tolerance for Gene's often wild escapades.

Jonathan gives Gene much needed support and friendship; in return Gene helps him with his self-esteem. Marilyn agrees to go out with Jonathan and they become very involved. At the same time, Gene and Bunny progress their relationship, with him talking about his future dream to own a horse stable.

After an evening scuffle at the local diner (instigated by the pompous Kenny) that results in some damage to the premises, Gene's father kicks him out. Having disappeared for weeks, Gene reappears on the night of the prom. Hunting down Jonathan, they go to the prom without tuxes. Marilyn has gone to the prom with her ex, a quarterback she dated the previous year, and Bunny has attended with Kenny.

The guys take off, with Bunny trying to chase after Gene. Just outside of town Jonathan and Gene stop and catch up. It turns out that Gene has relocated to Kentucky, where he has gotten work in a stable. He decided to come back for Bunny, but now feels she won't go with him. Jonathan goes to find her, Gene and Bunny reconcile, and they take off for Kentucky on his motorcycle.

Back in town, Jonathan informs Bunny's father that she's gone, stands up to Kenny by totaling his car and finally asks out classmate Rosalie, who recently had her braces removed.