Trama

After being kicked out of his rock band, Dewey Finn becomes a substitute teacher of an uptight elementary private school, only to try and turn his class into a rock band.

After being kicked out of his rock band, guitarist slacker Dewey Finn faces a mountain of debts and depression. He shares an apartment with his best friend, Ned Schneebly, an old band member who is now a substitute teacher. Dewey pretends to be his roommate Ned and accepts a job as a substitute teacher at a snobbish private elementary school where his attitude and hijinks have a powerful result on his students. He learns they are talented young musicians, and he decides to form a rock band with them to win the $20,000 prize money in a local band contest. Once Dewey wins a competition called "Battle of the Bands", the prize money would solve his financial problems and put him back in the rock music spotlight.—Steve Shedloski

After being fired from his own rock band, guitarist slacker Dewey Finn needs to raise some money to pay for his rent and his bills. When his best friend and substitute teacher Ned Schneebly is called to a temporary work in an expensive private school, Dewey pretends to be Ned and accepts the job. He finds talented young musicians in his class, and he decides to form a rock band with the students to play in a local band contest. However, he must do this secretly so that the school's principal and the students' parents know nothing about his plan. Once Dewey wins a competition called "Battle of the Bands", he can raise the $20,000 prize money and be recognized in the rock music business. He and his class do everything to prepare themselves for the competition without anyone else discovering the real truth.—Claudio Carvalho, Rio de Janeiro, Brazil

Dewey Finn (Jack Black) is a guitarist of an unpopular rock band No Vacancy. Dewey's arrogance and hyperactive stage antics causes various disadvantages for the band mates. The next day, No Vacancy votes Dewey out of the band and replaces him with another guitarist named Spider (Lucas Babin). Furthermore, Dewey's submissive roommate and lifelong friend, Ned Schneebly (Mike White), is pressured by his girlfriend, Patty Di Marco (Sarah Silverman), to evict Dewey unless he gets a real job to pay back his growing rent debt. Dewey thinks about having to quit music until he receives an urgent phone call intended for Ned from Rosalie Mullins (Joan Cusack), the principal of a prestigious prep school, Horace Green, asking Ned to replace for a teacher who broke her leg.

Desperate for income to avoid getting evicted, Dewey impersonates Ned and takes the substitute teacher position for a fourth-grade class. Upon appearing in the classroom, he requests the students to call him "Mr. S." after failing to spell "Schneebly" on the blackboard. However, Dewey incompetently resorts to grimacing over his rental problems and unemployment and allows his students to do anything.

Occasionally, Dewey gives casual and non-motivational lectures to the class. When Dewey overhears his students playing in music class, he thinks that the children of his class are musically talented and decides to make his personal project by converting the class into a rock band and crew to serve as a vehicle to stardom by winning the upcoming Battle of the Bands, where he is out to avenge his eviction from his old band and win the $20,000 prize.

When Dewey realizes the kids are mostly interested in pop and hip-hop, he turns the school days into lessons of rock history as well as playing rock music, exposing his students to those artists he regards as rock legends. Many rock legends are featured in classic photos and footage during a montage scene, including Led Zeppelin, The Ramones, Jimi Hendrix, Pink Floyd, Iggy Pop, The Who, Rush, The Clash, Nirvana, AC/DC, Black Sabbath and David Bowie. Dewey narrowly avoids detection when Rosalie decides to attend one of his class' lessons to check on their progress, forcing him to attempt to teach the actual course material. Dewey attempts to make friends with her through rock music, by playing her favorite song "Edge of Seventeen" by Stevie Nicks on a jukebox while visiting a bar.

The two become close friends and the class auditions for Battle of the Bands, which Dewey informed them was their "school project". They are rejected because they show up too late despite the bill being full. With the help of class factotum and band manager Summer Hathaway (Miranda Cosgrove), Dewey persuades the venue's managers to allow the students perform in Battle of the Bands by lying that the students are orphans and have been diagnosed with a blood disease.

Dewey becomes exposed when the real Ned receives a paycheck from Horace Green in the mail, although he doesn't work there. He attempts to call the school about this, but Dewey breaks the call and confesses everything to Ned. He urges Ned not to inform Patty, but she manages to reveal the truth out of Ned. During a parents' meeting later on, Dewey meets the students' parents, who initially scrutinize Dewey's teaching abilities, utilizing the fact that their children were becoming more engrossed in music rather than the usual schoolwork. Ned eventually appears with the police and confronts Dewey under pressure from Patty. When Rosalie appears, his real identity is revealed, causing Dewey to become sacked.

The next day, the class decides they have still put too much work into not do the final show at Battle of the Bands, so Summer arranges the class trip. They stop at Dewey's apartment in an attempt to give him new energy and have him join them. Rosalie discovers the children leave for the concert and informs their parents who are all in her office wanting answers from the events of the previous day. The parents and Rosalie, informed by a phone call from Patty, head to the concert venue to take their kids back. Meanwhile, Ned eventually stands up to Patty and leaves her to go to the concert, much to her extreme dismay.

At the concert, the band plays their eponymous song, written by their lead guitarist, Zack Mooneyham (Joey Gaydos Jr.). Regardless of the audience's reception and winning over the crowd, School of Rock loses to No Vacancy, but accept their defeat due to Dewey's earlier proclamation that they were there not to win but rather to play "one great show". However, the audience (except one member) becomes distressed by No Vacancy's winning acceptance and demand School of Rock for an encore. The band returns to the stage to play a cover of "It's a Long Way to the Top (If You Wanna Rock 'n' Roll)" by AC/DC with an altered ending.

The song segues into the film's closing credits. Summer is seen calling on her cell phone as she enters the School of Rock, a newly opened after-school program where Dewey continues to coach the band itself while Ned teaches beginner music students. The closing credits roll as the class, breaking the fourth wall, sings "The movie is over, but we're still on screen."