Billy Madison is a non-working, non-educated slacker who lives entirely off his dad. He spends his day drinking beer, reading girly magazines, and hanging out by the pool. When his father realizes that Billy is unfit to run the family business, Billy decides that he must go back to school and earn a real education. He figures it will be no problem going back to high school and learning over again, until he learns that his father bought Billy's passing grades all the way back in elementary school. Thus, Billy must return to elementary school and pass each grade one at a time in a short time, or else he loses his place as heir to the company. In addition, Billy tries to win the hand of Veronica, a sexy school teacher who thinks her students are more mature than Billy.