Ferris Bueller's Day Off is a 1986 American teen comedy film written, co-produced, and directed by John Hughes. The film stars Matthew Broderick, Mia Sara, and Alan Ruck, with supporting roles from Jennifer Grey, Jeffrey Jones, Cindy Pickett, Edie McClurg, Lyman Ward and Charlie Sheen. It tells the story of the eponymous character, a charismatic high school slacker who lives in Chicago and skips school with his best friend Cameron and his girlfriend Sloane for a day, regularly breaking the fourth wall to explain his techniques and inner thoughts.

Hughes wrote the screenplay in less than a week. Filming began in September 1985 and finished in November, featuring many Chicago landmarks including the Sears Tower, Wrigley Field, and the Art Institute of Chicago. The film was Hughes's love letter to Chicago: "I really wanted to capture as much of Chicago as I could. Not just in the architecture and landscape, but the spirit."

Released by Paramount Pictures on June 11, 1986, the film became the tenth-highest-grossing film of 1986 in the United States, grossing $70 million over a $5 million budget. The film received generally positive reviews from critics and audiences alike, who praised Broderick's performance, and the film's humor and tone. In 2014, the film was selected for preservation in the United States National Film Registry by the Library of Congress, being deemed "culturally, historically, or aesthetically significant". The film was followed by a television series, starring Charlie Schlatter as the title character. A spin-off film titled Sam & Victor's Day Off, focusing on the two valets who took Cameron's father's Ferrari on a joy ride, is in development for Paramount+.

One spring day in a Chicago suburb, high school senior Ferris Bueller fakes illness to stay home from school, two months before his graduation, regularly breaking the fourth wall to describe his senioritis. His parents, Katie and Tom, believe he is ill, though his sister, Jeanie, does not. After learning Ferris has been absent nine times that semester, the school's dean, Edward Rooney, and his secretary Grace become determined to expose Ferris's chronic truancy; Ferris hacks into the school's computer system and reduces his absence count to two, making it appear that he attends school regularly.

Ferris persuades his hypochondriac best friend Cameron Frye to help excuse Ferris's girlfriend Sloane Peterson from school by claiming that her grandmother has died. Cameron calls the school, pretending to be Sloane's father. Knowing Sloane is dating Ferris, Rooney and Grace are suspicious. Ferris also calls the school during Cameron's phone call to confirm his absence, thereby fooling Rooney into believing he offended Sloane's father. To complete the ruse that Sloane's father is picking her up from school, Ferris borrows the prized possession of Cameron's father, a 1961 Ferrari 250 GT California Spyder. Fearing his father's wrath, Cameron is dismayed when Ferris takes the car on a day trip into Chicago. Ferris promises they will return the car as it was, including preserving the original odometer mileage.

Ferris, Cameron, and Sloane leave the car with two parking attendants, who promptly take it on a long joyride. The three eat lunch at an upscale restaurant, visit the Art Institute of Chicago, go to a Chicago Cubs baseball game, and attend the Von Steuben Day Parade, where Ferris jumps on a float and lip syncs to "Danke Schoen" by Wayne Newton and "Twist and Shout" by The Beatles, all while hiding from his father, who works in the city.

Meanwhile, Rooney prowls the Bueller home for Ferris, becoming victim to several pratfalls and pursued by the family's pet Rottweiler. Jeanie skips class and returns home to confront Ferris, and discovers a dummy in his bed, while finding Rooney there. Mistaking him for a burglar, she knocks him unconscious and calls the police. Rooney regains consciousness and leaves the house upon discovering his car being towed. The police arrest Jeanie, believing she prank-called the police station. While detained, she befriends a young delinquent who advises her to worry less about Ferris's exploits and more about her own life.

Upon collecting the Ferrari and heading home, Ferris and Cameron discover that the car's mileage has significantly increased due to some mechanics joy-riding in it. Cameron enters semi-catatonic shock, later almost drowning in a pool before a worried Ferris helps him. At Cameron's house, Ferris jacks up the car and puts it in reverse gear to unsuccessfully attempt to rewind the odometer. Angry toward his domineering father, Cameron wrecks the car by launching it out the garage's rear window. Ferris offers to take the blame, but Cameron decides to tell the truth and stand up to his father. After walking Sloane home, Ferris remembers his parents will be returning home soon. He runs through the neighborhood and is nearly hit by Jeanie's car as Jeanie and Katie drive home. Katie fails to notice Ferris, though Jeanie does, and attempts to bolt home while the police catch her speeding.