American Reunion (also known as American Pie 4: Reunion or American Pie: Reunion in certain countries) is a 2012 American sex comedy film written and directed by Jon Hurwitz and Hayden Schlossberg. It is the fourth and final installment in the American Pie theatrical series. The film's ensemble cast features many actors who reprise their roles from the previous three films, including Jason Biggs, Alyson Hannigan, Chris Klein, Thomas Ian Nicholas, Seann William Scott, Eddie Kaye Thomas, Eugene Levy, Tara Reid, and Mena Suvari, among others. The film follows former East Great Falls High School classmates who return to their hometown for a reunion for their graduating class.

Released in the United States on April 6, 2012, American Reunion received generally mixed reviews from critics, but was a worldwide box office success, grossing $235 million against a $50 million budget.

Nine years after getting married, Jim Levenstein and his wife Michelle are in a sexual rut following the birth of their 2-year-old son. Kevin Myers is a househusband and architect, Chris "Oz" Ostreicher is a celebrity sportscaster dating Mia, a superficial supermodel, and Paul Finch has been traveling the world. The four friends return from their disparate locations to East Great Falls, Michigan, for their thirteen-year high school reunion. They are unintentionally joined by Steven Stifler, whom they hoped to avoid. Jim encounters Kara, a former neighbor who he used to babysit. She invites him to her 18th birthday party and he reluctantly accepts.

The guys spend the following day at the lake with Michelle and her friend Selena, whom Finch bonds with. Kevin and Oz reunite with their high school girlfriends Vicky and Heather, and meet Heather's boyfriend, Ron. Kara's boyfriend AJ steals bikini tops from Mia and other women before fleeing on a jet ski. The guys track AJ and his friends to a nearby beach where Jim overhears AJ's boastful plans to take Kara's virginity. Stifler destroys their jet skis and the guys flee.

Instead of spending time with Michelle, Jim accompanies the others to the falls where they find Kara's party. Unsatisfied with Heather, Ron suggests swapping girlfriends to a disgusted Oz. Kara drunkenly tries to seduce Jim, but he rejects her. When she passes out, Jim recruits Stifler, Finch, and Oz to distract her parents while he sneaks her into her bedroom. Jim returns home and falls asleep, further leaving Michelle despondent about their marriage. The following morning, Kevin wakes up in bed with Vicky and assumes they had drunken sex. She confirms they did not but is upset he thinks so lowly of her.

Jim encourages his widower dad Noah to begin dating, so they bring him to Stifler's house party where he meets Stifler's mother, Jeanine. Oz admits his continued feelings for Heather; Mia finds out and breaks up with him. Jim waits upstairs for Michelle so they can have sex, but Kara again tries to seduce him. AJ intervenes and a fight ensues. Jim explains the situation to Michelle and states he does not care about Kara, causing both women to leave upset. The police arrive and arrest Finch for stealing a motorbike. Stifler mocks Finch, and the guys confront him over being a bad friend and his inability to move on from high school. Stifler reminds them that they have ignored and avoided him for years.

The next day, Noah offers Jim advice on repairing his marriage. At the reunion, Finch admits that he lied about his travels because he was embarrassed to admit that he has a normal job as a retailer manager and stole the bike from his neglectful boss. Feeling guilty about their treatment of Stifler, the guys visit him at work and apologize, solidifying their friendship. Stifler confronts his verbally abusive boss and quits.

The guys returns to the reunion together where Kevin reconciles with Vicky, Finch makes amends to Selena, Oz and Heather choose to be together, and Jim and Michelle finally have sex. Stifler is offered work as a wedding planner and is seduced by Finch's mother, Rachel.