The school board meets to welcome Miss Evelyn Togar (Mary Woronov
), Vince Lombardi High School's new principal -- the old principal having been driven insane by the unruly students. Riff Randell (P.J. Soles
) and her nerdy friend Kate Rambeau (Dey Young
) hijack the PA system to play some music ("Sheena Is a Punk Rocker"). Miss Togar interupts the dance party and gives them both detention. Miss Togar then announces to the assembled students that Vince Lombardi High School has the worst academic standing in California. Three principals in a row have suffered nervous breakdowns because the student body cares about nothing but rock and roll music. Miss Togar vows to the students that she will clean up the school and make it a center of learning. Intimidated, the kids rush off to their classes.
Kate has a crush on the quarterback, Tom Roberts (Vincent Van Patten
), who has the hots for Riff. Tom is shy with girls -- all he can think of to talk about is the weather -- so rather than ask Riff out, he goes to see the school's fixer, Eaglebauer (Clint Howard
), who has an office in the boys' restroom. Eaglebauer agrees to get Tom a date with Riff. His task becomes complicated the very next day when Kate asks him to get her a date with Tom.
Riff, an aspiring singer and songwriter, has written a song called "Rock 'n' Roll High School" for her favorite band, the Ramones. Her heart belongs to lead singer Joey Ramone
, and she hopes that one day she'll be able to give the song to Joey and that the band will record it.
Miss Togar sends her two geek minions, hall monitors Fritz Hansel (Loren Lester
) and Fritz Gretel (Daniel Davies
), to summon Mr. McGree (Paul Bartel
), the music teacher, and Coach Steroid (Alix Elias
), the gym teacher, to the science lab. Togar has been researching the effects of rock music. She shares her findings with Mr. McGree and Coach Steroid, and performs a demonstration: Ramones music played at high decibel levels makes mice explode. Meanwhile the girls' gym class, left unsupervised, is rocking out to unauthorized music -- Riff singing along to her demo tape of "Rock 'n' Roll High School". Fritz Hansel and Fritz Gretel happen by and rat the girls out, but before Togar arrives, the class goes back to the boring calisthenics they were supposed to be doing.
In the girls' locker room, Riff announces that the Ramones are coming to town to give a concert and she plans to go. The other girls, though enthusiastic, can't take time away from school to wait in the ticket line for three days. Riff resolves to get tickets for everyone.
At the concert hall, Riff is first in line. She sets up a folding lounge chair and settles in to wait. Back at school, Kate gives Miss Togar notes with increasingly implausible excuses to cover for Riff's absence: the death of her mother, the death of her father, and the death of her goldfish. (Hansel and Gretel disprove this excuse by producing the goldfish, which seems perfectly healthy until one of them swallows it.) The ticket line gets longer and a groupie, Angel Dust (Lynn Farrell
), cuts in front of Riff to claim the first place in line. Their argument is interrupted by the arrival of the Ramones in a big old convertible, singing "I Just Want to Have Something to Do." The band's manager recognizes Angel Dust and invites her to come in with the band, much to Riff's chagrin.
When the ticket window finally opens, Riff buys 100 tickets and later distributes them at school. Miss Togar gets wind of the concert and demands that Riff and Kate surrender their tickets. When they refuse, Togar lets the hall monitors take the tickets by force ("body search!"). Disheveled and despondent at the prospect of missing the concert, the girls retreat to Riff's house to do homework.
Meanwhile, Eaglebauer is with Tom in Tom's tricked-out van, coaching him on how to ask Riff for a date. Tom calls just as Kate confesses to Riff that she thinks Tom will soon ask her (Kate) out. Kate is furious when Riff agrees to go out with Tom, but Riff assures her that she only accepted so she can fix up Tom and Kate.
In Riff's car, Kate and Riff hear a DJ giving away a pair of Ramones tickets on the radio. Frantic to win the tickets, Riff pulls the car over and they pull a man out of a phone booth (the poor guy's proposing to his girlfriend) so they can use the phone. When they hear they've won, Riff calls Tom to break their date and the girls rush back to Riff's place to dress for the show.
That evening, concert-goers file into the club, which is growing crowded. The kindly Mr. McGree attends out of curiosity, but his outdated idea of cool clubwear (a '50s-era beret and a '60s-era scarf) elicits some snickers. A large white mouse is denied admission -- the staff is afraid the music will cause him to explode -- until he produces a pair of noise-canceling headphones. An Indian chief in full feathered headdress is also attending.
Riff and Kate are introduced on stage by the DJ who ran the ticket contest, Screamin' Steve Stevens (Don Steele
). Offered the chance to say a few words to the crowd and the radio audience (which includes Miss Togar), Riff says "On behalf of the students from Vince Lombardi High who are here tonight, I'd just like to say one thing: Screw you, Principal Togar, we made it to the concert anyway!"
Screamin' Steve tries to get Riff and Kate backstage to meet the band, but the Ramones' manager isn't having any, and tells Angel Dust, the groupie, to see the girls back to their seats. The crowd is revved up and shouting "hey, ho! let's go!" when the band takes the stage to open with "Blitzkrieg Bop." Riff has to encourage Kate to get into it, but Kate begins to loosen up and enjoy herself during the next song, "Teenage Lobotomy." During the following number, "California Sun," Angel attempts to steal the song Riff wrote. Tom, who has come to the concert with Eaglebauer, chases her and gets hold of the package when Angel trips over a cokehead who's spilled his powder on the floor. Riff offhandedly thanks Tom for his help and runs back to the concert. Tom sees that only Kate really cares about him and they agree to be friends. Back on stage, Joey (reading a note from Riff) dedicates the next song, "She's the One," to Tom and Kate.
At the same time Miss Togar's minions, Hansel and Gretel, crash the concert looking for Riff. Instead they find Angel Dust in the Ramones' dressing room. When Angel Dust mouths off to them, they yell "body search!" and attack her. Riff eventually gets backstage to give Joey her song.
A few days later, Miss Togar and several concerned parents hold a rally where they try to burn a pile of Ramones records in front of the school. Riff and Tom throw a bowl of water at the bonfire and at Miss Togar. When most of the students begin to riot, the Ramones arrive and all the students cheer for them. Taking over the group, Riff, Tom, Kate, Eaglebauer and others storm the school and throw a large climactic party. Mr. McGree, finally seeing the ruthless and authoritarian figure that Miss Togar has become, defects and joins the students -- and the party -- in the school. Hansel and Gretel sneak in to stop the party, but when they're discovered hiding in a laundry cart, the Ramones themselves push the cart out of a third floor window. Miss Togar's henchmen end up in bandages and casts with multiple injuries.
During the party, Riff announces that the Ramones are honorary members of the student body. The Ramones give Riff a Ramones jacket and makes her an honorary member of their band. The band plays "Do You Wanna Dance" while Kate and Tom dance together and make out, having found love at last. The students proceed to party and wreck most of the building with the loud music.
But that evening, a furious Miss Togar calls the police and the building is surrounded by riot officers led by Chief Klein (Dick Miller
). When Miss Togar, speaking through a bullhorn, demands that the students stop the festivities, Riff responds by destroying all the mid-term exams and all the student records with a chainsaw. More angry than ever, Miss Togar and Chief Klein threaten to storm the building with tear gas unless the students exit the premises within five minutes.
With few options left, Kate and Eaglebauer devise a bomb in the laboratory. Aware that their party is finally over, the Ramones, Riff, Kate, Tom, Eaglebauer, Mr. McGree, and all the students quietly file out of the building where the riot police are poised to attack. Riff steps forward and tells Miss Togar that if she wants to have her school back, she can. When a surprised Togar asks Riff what she would have done with the school anyway, Riff says "Rock the roof off it! Hit it, Marky!" -- and the band launches into Riff's song, "Rock 'n' Roll High School." The students and Ramones resume their party and Riff detonates the bomb. The school explodes spectacularly.
As Vince Lombardi High School burns, fire trucks arrive. The students are led away, still happy and partying, to police buses waiting to take them to jail, while Miss Togar is taken away in an ambulance in a straight-jacket mumbling "detention" over and over. She has become the latest principle to be carted away to a mental hospital.