The film begins as Lizzie McGuire prepares for her junior-high graduation with one of her two closest friends, David "Gordo" Gordon. Her other best friend, Miranda, has chosen to skip the graduation ceremony in favor of a trip to Mexico City to visit relatives. During the ceremony, Lizzie trips onstage and accidentally brings the curtain down on her fellow graduates; this causes her to be teased by her ex-best friend, Kate Sanders, and her younger brother Matt. After graduation, Lizzie and her class embark on a trip to Rome, Italy, chaperoned by their future high school principal, the stern Angela Ungermeyer. To their dismay, Lizzie and Kate are assigned to the same hotel room.
Their class visits the Trevi Fountain, where Lizzie is approached by an Italian pop star named Paolo who mistakes her for his singing partner, Isabella. Paolo asks Lizzie to meet him at the fountain the next day, and she feigns illness to sneak away. He explains that he and Isabella are booked for the Italian Music Awards, but she left Italy after their breakup. Paolo tells Lizzie that Isabella lip syncs, and begs her to pose as Isabella for the concert. She reluctantly agrees, and begins to enjoy the designer clothes, dance rehearsals, and adoration from fans.
Lizzie continues to fake being ill to prepare for the concert, but Kate quickly figures out her secret. To Lizzie's surprise, Kate agrees to help her and the two become friends again. Lizzie begins to fall in love with Paolo, to Gordo's dismay. Ethan suspects Gordo is jealous of Paolo, though he insists otherwise. Meanwhile, Ms. Ungermeyer interrogates the students to learn who has been sneaking out. Gordo takes the blame, and is sent back home as punishment. Lizzie is shocked when Kate says that Gordo sacrificed himself to protect her.
At the airport Gordo meets Isabella, who has returned for the concert and is upset to hear that Lizzie is impersonating her. She and Gordo realize that Paolo is planning to cut Lizzie's microphone at the concert, demonstrating to the crowd that Isabella is a fake. Paolo's plan is to ruin Isabella's career and embarrass Lizzie. Gordo and Isabella rush to the concert to stop him. Back home, Matt browses the Internet and finds Italian gossip sites with pictures of Lizzie as Isabella. When he tells his parents, the family flies to Rome to stop Lizzie and bring her home. Ms. Ungermeyer realizes that Lizzie is missing again, and Ethan accidentally reveals that she is at the Italian Music Awards. The class rushes to the concert to find Lizzie. Gordo and Isabella find her backstage preparing for the show, and warn her about Paolo's scheme. Lizzie refuses to believe them at first, but Isabella insists that Gordo can be trusted and Paolo is using her.
During the performance Isabella and Gordo expose Paolo by turning on his microphone, revealing his real voice. Embarrassed, Paolo runs off and is ambushed outside by paparazzi. His bodyguard, Sergei, tells him it is time to face reality and quits. Sergei flirts with Ms. Ungermeyer, who has gotten the class and Lizzie's family into the concert by beating up the bouncers. Isabella introduces Lizzie to the crowd, and has her sing "What Dreams Are Made Of". As a singer, Lizzie gains a newfound confidence. Later, they celebrate at the hotel's after party. Ms. Ungermeyer rescinds Gordo's punishment, and Lizzie's parents, despite being proud of Lizzie, tell her she is grounded for the rest of the summer. Lizzie and Gordo sneak away from the party to go up to the roof. They promise to never let things change between them. The two kiss and rejoin the party.Hilary Duff as Elizabeth Brooke "Lizzie" McGuire/Isabella Parigi
Singing voice for Isabella Parigi provided by Haylie Duff
Adam Lamberg as David Zephyr "Gordo" Gordon, Lizzie's best friend
Robert Carradine as Samuel "Sam" McGuire, Lizzie and Matt's father
Hallie Todd as Joanne "Jo" McGuire, Lizzie and Matt's mother
Jake Thomas as Matthew "Matt" McGuire, Lizzie's little brother
Yani Gellman as Paolo Valisari
Alex Borstein as Ms. Angela Ungermeyer
Clayton Snyder as Ethan Craft, Lizzie and Kate's crush
Ashlie Brillault as Katherine "Kate" Sanders, Lizzie's popular ex-best friend who she later reconciles with
Brendan Kelly as Sergei
Carly Schroeder as Melina Bianco, Matt's best friend
Daniel R. Escobar as Mr. Escobar, the drama teacher/choir director at Hillridge Junior High School.
Jody Raicot as Giorgio
Terra MacLeod as Franca DiMontecatini
Claude Knowlton as the stage manager
Credits adapted from The New York Times.
The film, produced by Stan Rogow, was directed by Jim Fall from a screenplay by Susan Estelle Jansen, Ed Decter and John J. Strauss and filmed on location in Rome, Italy in the fall of 2002. All the series characters reprised their roles except for Lalaine (Miranda Sanchez), who left the series late in the second season to film the Disney Channel original movie You Wish! Her character was said to be on vacation with her family in Mexico City.
The film had a mixed critical reception based on 96 reviews on Rotten Tomatoes, giving a 40% overall approval rating. The site's consensus stated it was a "harmless piece of fluff that ought to satisfy fans of the TV show". Scott Brown of Entertainment Weekly gave the film a B+: "Let's face it: Lizzie McGuire (Hilary Duff) is just too darn polished to be a junior-high underdog, even by the standards of her 'luxe suburban environs'. But that hasn't tarnished her comeback-kid cred among the six-and-ups who faithfully follow her Disney Channel show—and it doesn't make The Lizzie McGuire Movie, a clever, agreeably weightless theatrical outing, any less enjoyable." Conversely, Roger Ebert gave the film two stars out of four, but praised Borstein's performance, calling her work "the only really delightful element in the movie; everything else is simply slick and professional."
In its opening weekend the film grossed $17,338,755 in 2,825 theaters in the United States and Canada, ranking second behind X2: X-Men United. By the end of its run, The Lizzie McGuire Movie grossed $42,734,455 domestically and $12,800,000 internationally for a worldwide total of $55,534,455.2003 (won): Teen Choice Award for Movie Breakout Star, Female (Hilary Duff)
2003 (nominated): Teen Choice Awards for Movie Comedy, Movie Comedy Actress (Hilary Duff)
2004 (nominated): Leo Award for Feature-Length Drama: Best Visual Effects (Gary Gutierrez, Jayne Craig, Bruce Woloshyn, Simon Ager and Wes Sargent)
The Lizzie McGuire Movie's soundtrack was released on April 22, 2003. It is composed primarily of songs from (or inspired by) the film, including Hilary Duff's "Why Not" and her sister Haylie's "Girl in the Band". "Why Not" was released as a single outside the United States on June 23, 2003 and later included on Hilary Duff's second album, Metamorphosis (with different lyrics in the first verse). The album has been certified platinum by the CRIA, and 2x platinum by the RIAA for selling 2,000,000 copies in the U.S.