Who's That Girl is a 1987 American screwball comedy film directed by James Foley, and written by Andrew Smith and Ken Finkleman. It stars Madonna and Griffin Dunne, and depicts the story of a street-smart girl who is falsely accused of murdering her boyfriend and is sent to jail. After release, she meets a man, supposed to make sure she gets on her bus back to Philadelphia, and convinces him to help her catch those responsible for her confinement. While searching for an embezzler, they fall in love with each other.

After her 1986 film Shanghai Surprise failed, Madonna decided to sign on to another comedy, titled Slammer, later renamed Who's That Girl. However, she had to convince both Warner Bros. and the film's producers that she was ready. Madonna enlisted her friend Foley to direct. Shooting began in New York in October 1986, and continued until March 1987. Production was halted during December due to snowfall. Madonna utilized the time to work on her next tour and the film's soundtrack.

The film was released on August 7, 1987, and was a box office bomb, grossing only $2.5 million in its first week, with its final domestic total being about $7.3 million on a budget between $17–20 million. Critics were highly dissatisfied with the film, and Foley's direction. However, the accompanying music tour went on to be a critical and commercial success, grossing a total of US$25 million, and playing in front of audiences totaling 1.5 million people. The soundtrack also enjoyed commercial success, selling over six million copies worldwide, in addition to the title track becoming Madonna's sixth number one single on the US Billboard Hot 100 record chart.