The Princess Diaries is a 2001 American coming-of-age comedy film produced by Walt Disney Pictures and directed by Garry Marshall. Based on Meg Cabot's 2000 young adult novel of the same name, the film was written by Gina Wendkos and stars Anne Hathaway and Julie Andrews, with a supporting cast consisting of Héctor Elizondo, Heather Matarazzo, Mandy Moore, Caroline Goodall and Robert Schwartzman. The film follows Mia Thermopolis (Hathaway), a shy American teenager who learns she is heir to the throne of a European kingdom. Under the tutelage of her estranged grandmother (Andrews), the kingdom's reigning queen, Mia must decide whether to claim the throne she has inherited or renounce her title permanently.

Feeling confident about the novel's film potential, Cabot's agent pursued producer Debra Martin Chase about adapting The Princess Diaries into a feature-length film, an idea she pitched to Disney upon reading the book. After obtaining the film rights, Disney originally greenlit the project under the title The Princess of Tribeca, reverting it once its setting was changed from New York to San Francisco, where the majority of the film was shot between September and December 2000. Marshall, who was known for helming several romantic comedies, agreed to direct because he found the story ideal for family entertainment. Despite having little involvement in the film's development, Cabot was consulted about various changes to its story and characters. Hathaway won the lead role over several established young actresses in her motion picture debut, while The Princess Diaries commemorated the end of Andrews' semi-retirement from acting and return to Disney films, her first since Mary Poppins (1964).

DETAILED PLOT

Mia Thermopolis is a student at Grove High School residing with her single mother, Helen, at a refurbished firehouse in San Francisco. Unpopular among her peers, Mia suffers from a fear of public speaking while harboring a crush on Josh Bryant, and is often teased by his popular girlfriend Lana Thomas. Mia's only friends are social outcast Lilly Moscovitz and Lilly's older brother, Michael, who secretly harbors feelings for her.

Mia learns from her estranged paternal grandmother, Clarisse, that she is sole heir to the European kingdom of Genovia, having inherited the throne from her recently deceased father Philippe. Clarisse is determined to groom Mia into a refined princess so that she may one day rule the kingdom over which Clarisse currently presides. Overwhelmed by the discovery, Mia initially refuses until Helen convinces her to attend her grandmother's "princess lessons" on the condition that she need not make her final decision until the Genovian Independence Day Ball in three weeks' time.

Mia receives a glamorous makeover and a limousine chauffeured by Joe, the queen's head of security and confidante, who becomes a father figure to her. Mia's transformation causes her schoolmates to treat her differently, while her increasingly hectic schedule strains her relationship with Lilly. To appease her best friend, Mia tells Lilly the truth and swears her to secrecy. However, the public soon learns that Mia is a princess after the secret is sold to the press by Paolo, the hairdresser responsible for Mia's makeover, and the paparazzi begins to pursue her relentlessly. Although Mia embarrasses herself at her first state dinner, the queen admits that she found her clumsiness endearing and suggests that they spend quality time together, canceling their lessons for the following afternoon. While bonding, Clarisse explains that although Mia's parents loved each other, they divorced amicably in order to pursue their own passions, Philippe remaining in Genovia to eventually become King, and Helen returning to America with Mia to offer her a "normal" childhood.

As Mia's popularity grows, Josh invites her to attend a beach party with him. Mia accepts, causing her to neglect Lilly and forgo her plans with Michael. The paparazzi ambushes Mia at the beach party. Josh kisses Mia in front of the paparazzi to get his "15 minutes of fame", while Lana helps the paparazzi photograph Mia wearing only a towel; both photographs are printed in the newspaper the following day. Finding the photos inappropriate for a princess, Clarisse admonishes Mia for her behavior, after which a humiliated Mia promises to renounce her title. Joe reminds Clarisse that Mia is still both a teenager and her granddaughter, suggesting that the queen reacted too harshly.

After making amends with Lilly, Mia finally stands up to Lana for bullying a schoolmate. Mia invites both Lilly and Michael to the ball but Michael declines, still heartbroken over Mia's initial dismissal. After Clarisse apologizes to Mia for scolding her, she states that Mia must publicly renounce the throne at the ball. Terrified by the prospect, Mia plans to run away until she discovers a touching letter from her late father and relents. Mia's car malfunctions while driving to the ball, stranding her in a downpour until she is retrieved by Joe.

When they finally arrive, Mia, still wet and untidy from the rain, accepts her role as Princess of Genovia while Clarisse, Helen and Lilly look on proudly. After changing into a gown, Mia accompanies Clarisse into the ballroom where Michael, who has accepted Mia's apology, invites her to dance before proceeding to the courtyard, where they confess their feelings for each other and share their first kiss. In the final scene, Mia is shown traveling to Genovia in a private plane with her pet cat Fat Louie, and writes in her diary that she plans to relocate to Genovia with her mother.