In the first scene of the film Jim Carroll is being spanked in front of his classmates by his teacher. When the teacher is finished he tells Jim "We can do it again tomorrow if you like Mr. Carroll". After this Jim and his friends Pedro (James Madio), Mickey (Mark Wahlberg), and Neutron (PAtrick McGaw) are on the Staten Island ferry. They then sniff Carbona cleaning fluid to get high. After Pedro gets a little too high he accidentally pukes on another man's head. The man chases them as they make their escape to their high school where they play a match of basketball. During the match Pedro steals from the opposing team's locker. After the match their coach Swifty (Bruno Kirby) brings them for burgers as a reward for winning the match. At the restaurant the other team confronts them about the theft and then Jim and his friends assault them.
Jim then visits his best friend Bobby (Michael Imperioli) in hospital who is dying from leukemia. Jim then takes Bobby to a strip show. Jim then meets Reggie (Ernie Hudson) and they play some basketball together. After this Jim and his main friends go to a cliff to jump into the river below it to prove they're brave. Jim and Mickey then go to prostitute twins Winkie and Blinkie. This is where Jim nervously tries cocaine for the first time.
The next scene is at Bobby's funeral. When the funeral is over Jim and his friends go to the basketball court and talk about Bobby's life. Mickey says "That kid was in so much pain, it's better that he died" Jim disagrees with this and they get into an argument over it. Jim describes his first time using heroin. In the film he is seen running through a field of flowers to describe the immense pleasure he felt.
In basketball practice Swifty takes Jim into the bathroom and offers him money in exchange for sexual favors. Jim refuses. Before a basketball game against Harlem High, Jim, Pedro, and Mickey pick pills from Pedro's hat, hoping they are uppers; Neutron is there, but he refuses the pills. Unfortunately, the pills are downers, and the boys are stumbling all over themselves on the court. Swifty pulls them out of the game and lectures them in the locker room, telling Jim he'll never play basketball there again. Jim and Mickey quit the team and drop out of school. Neutron stays.
Jim's mother then finds the pills he has been using. They get into an argument and she kicks him out of the house for saying "F@ck off". In the next scene Pedro tells Jim and Mickey about this guy who he is meant to deliver a car to. They steal the car but when they go the man to deliver it to him they realize they parked it in a "No-Parking Zone" and they see the car being towed away. The man gets mad at them and breaks Mickey's arm. Jim, Mickey and Pedro break into a shop but they experience trouble getting the cash register to open. They hear the cops coming and Jim and Mickey escape but Pedro is too late and gets arrested.
Jim passes out in the snow high off heroin and Reggie comes and takes him up to his apartment and forces him to detox. Jim screams in pain from the withdrawal and begs for some heroin.
Jim and Mickey buy some heroin off a drug dealer but when they find out that the drug dealer ripped them off Mickey chases him across the town and up onto a roof and pushes him off. Mickey then tries to escape but is beaten up by a gang and then arrested by the police. Jim then goes to his mother's apartment and begs to be let in. She refuses and talk to him through the locked door. Jim tells her that he is in some trouble and needs some money and needs to get out of town for a bit. His mother then calls the police. Jim sentenced to six months at Riker's Island for assault, robbery, resisting arrest, and possession of drugs. He does the whole stretch.
In the final scene Jim approaches the stage door to give his poetry reading. Pedro stops him and, to celebrate his release from Riker's, offers him a bag of dope. Jim refuses. The film ends with Jim reciting his work before an audience.