Four high school seniors from western Michigan are good friends: Jim Levenstein (Jason Biggs), an awkward, nerdy and sexually naïve character whose dad Noah (Eugene Levy) attempts to offer sexual advice including purchasing and giving him pornography; Chris "Oz" Ostreicher (Chris Klein), a member of the high school lacrosse team; Kevin Myers (Thomas Ian Nicholas), their geeky leader who wants to lose his virginity with his girlfriend named Vicky (Tara Reid); and Paul Finch (Eddie Kaye Thomas), a mochaccino-drinking sophisticate and a nerd. They are four outsiders who are geeks, usually get laughed at by arrogant jock Steve Stifler (Seann William Scott). These four boys make a pact, at Kevin's prompting, to lose their virginity before their high school graduation after a dorky classmate, Chuck Sherman (Chris Owen), claims to have done so at a party hosted by Stifler an ignorant and obnoxious lacrosse player who happens to be a close friend of the group (to a lesser degree, Finch, with whom he has a love-hate friendship).
Sixteen-year-old Minnesota high-schooler Juno MacGuff (Ellen Page) discovers she is pregnant with a child fathered by her friend and longtime admirer, Paulie Bleeker (Michael Cera). She initially considers an abortion. Going to a local clinic run by a women's group, she encounters outside a schoolmate who is holding a rather pathetic one-person pro-life vigil. Once inside, however, Juno is alienated by the clinic staff's authoritarian and bureaucratic attitudes. She is particularly offended by their calling her "sexually active", a term which she feels demeans the highly emotional event by which she became pregnant. All of this decides her against abortion, and she decides to give the baby up for adoption. With the help of her friend Leah (Olivia Thirlby), Juno searches the ads in the Pennysaver and finds a couple she feels will provide a suitable home. She tells her parents, Mac (J.K. Simmons) and stepmother, Bren (Allison Janney), who offer their support. With Mac, Juno meets the couple, Mark and Vanessa Loring (Jason Bateman and Jennifer Garner), in their expensive home and agrees to a closed adoption.
In an upscale New York City mansion, wealthy and popular Kathryn Merteuil (Gellar) is discussing her prep school with Mrs. Caldwell (Christine Baranski) and Caldwell's daughter Cecile (Selma Blair). Kathryn promises Mrs. Caldwell that she will look out for the sheltered and naive Cecile. Sebastian (Phillippe) enters and Mrs. Caldwell reacts to him coldly and leaves with Cecile. Kathryn reveals that her real intention is to use Cecile to take revenge on Court, her ex-lover, who had dumped her for Cecile. Kathryn asks her step-brother Sebastian to seduce Cecile; he refuses as he is planning to seduce virgin Annette Hargrove (Witherspoon), the daughter of their school's headmaster. Annette is a 'paradigm of chastity and virtue' who recently wrote a published essay about saving herself for marriage and has been temporarily staying with Sebastian's aunt. The two make a wager: If Kathryn wins, she gets Sebastian's vintage Jaguar XK140; if Sebastian wins, Kathryn will have sex with him. It is mentioned that Sebastian keeps a journal detailing his conquests.
Joe (Matthew Barry) is the son of famous opera singer Caterina Silveri (Jill Clayburgh). While Joe believes that Caterina's husband, Douglas Winter (Fred Gwynne), is his biological father, the truth is that he was sired by Caterina's former lover, who is now living in Italy and working as a schoolteacher. Joe is moody and rebellious and needs a strong father figure to guide him and keep him in line, but Douglas is ineffectual and emotionally weak, and when Joe witnesses the sudden death of Douglas, it sends him over the edge. In hopes of boosting her singing career, which has fallen into a rut, Caterina decides to move to Italy with her son. There, Joe falls in with a dangerous crowd and becomes addicted to heroin.
In the Victorian period, two young cousins, Richard and Emmeline Lestrange, and a galley cook, Paddy Button (Leo McKern), survive a shipwreck in the South Pacific and reach a lush tropical island. Paddy cares for the small children and forbids them by "law" from going to the other side of the island, as he found evidence of remains of bloody human sacrifices. He also warns them against eating a scarlet berry which is apparently deadly.
In 1984, Donny Berger's teacher, a hebephile named Mary McGarricle (Eva Amurri Martino), begins a sexual relationship with him. When she is discovered inciting him to sexual activity on a piano during an assembly, she is sentenced to a lengthy prison term where it is revealed she is pregnant. The court gives custody of the unborn child to Donny's abusive father until Donny himself is at the legal age to assume custody.
Anita "Needy" Lesnicki, once an insecure and bookish teenager living near Devil's Kettle, Minnesota, is now a violent mental inmate who narrates the story as a flashback while in solitary confinement. She has been friends with a selfish and popular cheerleader, Jennifer Check, since childhood, despite having little in common. One night, Jennifer takes Needy to a local dive bar to attend a concert by indie rock band Low Shoulder. A suspicious fire engulfs the bar, killing several people, and Jennifer, who is in shock, agrees to leave with the band despite Needy's protests. Later that evening, Jennifer, covered in blood, appears in Needy's kitchen and proceeds to eat food from the refrigerator. Unable to digest the matter, she vomits a trail of black, spiny fluid and then leaves in a hurry as Needy calls after her.
In 1963, thirteen-year-old Anne and fifteen-year-old Frederique are two Jewish sisters whose parents are separated. They live in Paris with their mom and spend their summer holidays at the beach with their father, around whom they both feel awkward. They attend a strict school.
The film opens with 16-year-old Telly (Leo Fitzpatrick) and a 12-year-old girl who are making out on a bed. With no adults around, Telly convinces the girl, who is a virgin, to have sex with him. Afterwards, he meets his friend, Casper (Justin Pierce), and tells him about his sexual experience in graphic terms. They go inside a local store, where Casper shoplifts a bottle of malt liquor as Telly distracts the cashier. Looking for drugs, food and a place to hang out, they head to their friend Paul's (Sajan Bhagat) apartment, though they express dislike of him on the way there. They arrive at Paul's house, talk about sex and smoke marijuana while watching a skate video (Video Days). Casper inhales nitrous oxide out of balloons, which Telly considers dangerous. The scene intercuts with a group of girls, among them Ruby (Rosario Dawson) and Jennie (Chloë Sevigny), talking about sex—each gender contradicting what the other gender says, especially about oral sex.
Max Fischer, a mature and eccentric 15-year-old, is a scholarship student at Rushmore Academy, a private school in Houston. He is both Rushmore's most extracurricular and least scholarly student. He spends nearly all of his time on elaborate extracurricular activities, caring little how it affects his grades. He also feuds with the school's headmaster, Dr. Guggenheim.
Matthew (Michael Pitt) is an American exchange student who has come to Paris to study French. While at the Cinémathèque Française protesting the firing of Henri Langlois, he meets the free-spirited twins Théo (Louis Garrel) and Isabelle (Eva Green). The three bond over a shared love of film.
Hervé (Vincent Lacoste) is a teenage boy in junior high school with ordinary looks and middling grades, living with his single mother in a housing estate in Rennes. He and his best friend Camel (Anthony Sonigo) often fantastize about their female classmates and their mothers, but have less luck with girls in reality.
Isabelle is on summer holiday with her family in the south of France. The film opens with a scene of voyeurism when Isabelle's younger brother, Victor uses binoculars from a cliff to watch his sister sunning topless on a beach. She then decides to have sex for the first time with a German boy named Felix, but the experience leaves her cold.
On October 2, 1988, Donnie Darko (Jake Gyllenhaal), a troubled teenager living in Middlesex, Virginia, is awakened and led outside by a figure in a monstrous rabbit costume, who introduces himself as "Frank" and tells him the world will end in 28 days, 6 hours, 42 minutes, and 12 seconds. At dawn, Donnie returns home to find a jet engine has crashed into his bedroom. His older sister, Elizabeth (Maggie Gyllenhaal), informs him the FAA investigators do not know where it came from.
Melissa (Valverde) is a shy 15-year-old virgin who feels increasingly distant from her family. Her father works on a foreign oil rig and her mother (Sacci) is too preoccupied with her housewife persona to notice that something is wrong with her daughter. The only person that senses Melissa's discomfort is her grandmother, Elvira (Chaplin). However, Melissa feels completely isolated when Elvira is carted off to a retirement home.