Andie Walsh (Molly Ringwald), a poor but fashion-conscious New Wave girl who has a crush on one of the rich boys in her school, Blane McDonough (Andrew McCarthy). When Andie and Blane try to get together, they encounter resistance from their respective social circles.

Andie lives on “the wrong side of the tracks” with her unemployed father (Harry Dean Stanton) who is struggling with depression after Andie’s mother abandoned the family some years before. Her best friend is Duckie Dale (Jon Cryer). Duckie has intense feelings for Andie, but plays it off as a joke in front of her. In school, she and Duckie are harassed by friends of Blane, the so-called “richie” kids Benny (Kate Vernon) and Steff (James Spader). Steff is attracted to Andie as well, but she knows he’s only after sex.

Andie works at TRAX, a New Wave music store in the Chinatown neighborhood of Chicago, managed by her older friend and mentor Iona (Annie Potts), whose quirky and unconventional dress sense is more influenced by her personal tastes than by her age group, and moans about her newly single life. Iona advises Andie to go to her senior prom despite not having a date. Blane and Andie talk for a brief moment as Blane buys an album.

Soon, Blane makes his move via chatting in the computer lab and Andie is smitten. Blane ventures out to the area at school where thepunks, metalheads, and New Wavers hang out during lunch and after classes, and asks Andie on a date. Steff begins questioning why his best friend “was conversing with a mutant,” but Blane brushes him off.

On the Friday night of the date, Andie waits for Blane at TRAX, but he is late. Duckie arrives instead, only to find Andie upset because she thinks she’s been stood up. When Blane finally arrives, Duckie and Andie argue. Duckie tries to convince her that Blane will only hurt her. After a few harsh words, Duckie storms out, and Andie goes on her date.

First, Blane suggests going to a party Steff is throwing. But the party isn’t exactly what Blane expected, and Andie is treated poorly by everyone, including a drunk Steff and Benny. Andie, in turn, suggests going to CATS, the local club, where they discover Iona sitting with Duckie. Duckie is immediately hostile toward Blane, and as he and Andie start walking out of the club, Duckie kisses a startled Iona.

Blane offers to take Andie home, but she finally admits she doesn’t want him to see where she lives. However, he drops her off there and they kiss, after he asks Andie to the prom. The next day, Andie visits Iona in her loft. Iona begins reminiscing about her own prom, donning her old pink prom dress and a beehive hairstyle.

At home, Andie’s father surprises her with a pink dress he bought for her at the thrift shop. Questioning how he was able to afford it, Andie discovers he has been faking going to a full-time job. The two begin to fight until her father breaks down, obviously still bitter and depressed about his wife having left him. Andie responds by comforting him and they make up but she, too, is affected by the abandonment of her mother.

Meanwhile Blane, pressured by Steff, begins distancing himself from Andie. He avoids her at school and doesn’t return her calls. She finally confronts him. He claims that he had asked someone else to go to the prom with him before he’d asked her, but had forgotten. Andie runs away, heartbroken. Duckie overhears Steff trashing Andie and they end up fighting in the hallway. Teachers stop the fight, and Duckie runs out.

Andie finds Iona preparing for a date with a yuppie, dressing like a normal adult for a change. Iona is already thinking about marriage. At first she is too wrapped up in her new romance to notice that Andie is upset. But her newly found happiness inspires Andie and she goes home with her friend’s old dress and creates a new pink dress in which she decides to attend the prom to “show them they didn’t break [her].”

When she gets to the prom she has second thoughts about braving the crowd on her own. Just as it looks like she may back out, she sees Duckie, also dressed up. They walk into the ballroom hand in hand. Steff snickers and begins trashing Andie and Duckie again, only to be finally told off by the normally passive Blane, who says that Andie could never be bought. Blane shakes Duckie’s hand and tells Andie that he always believed in her, he just didn’t believe in himself. He says he’ll always love her no matter what and leaves the prom. Duckie concedes that she was right, “He’s not like the others” and advises Andie to go after him. After Andie leaves, a blonde girl (Kristy Swanson) notices Duckie and silently invites him to go over and dance with her.

Outside of the prom, Andie catches up with Blane in the parking lot just before he gets to his car and they share a kiss.