Change of Habit is a 1969 American crime drama musical film directed by William A. Graham, and starring Elvis Presley and Mary Tyler Moore. Written by James Lee, S.S. Schweitzer, and Eric Bercovici, based on a story by John Joseph and Richard Morris, the film is about three Catholic nuns, preparing for their final vows, who are sent to a rough inner city neighborhood dressed as lay missionaries to work at a clinic run by a young doctor. Their lives become complicated by the realities they face in the inner city, and by the doctor who falls in love with one of the nuns.

The film was produced by Joe Connelly for NBC Productions and distributed by Universal Pictures. Filmed on location in the Los Angeles area and at Universal Studios during March and April 1969, Change of Habit was released in the United States on November 10, 1969. It spent four weeks on the Variety Box Office Survey and peaked at #17 among the year's highest grossing films.

Change of Habit was Elvis Presley's 31st and final film acting role and stars as a professional man for the only time in his career. There was interest in this film being a major Oscar contender, but Elvis manager Colonel Tom Parker knew the Academy's bias against Elvis ensured it was not considered. He famously said "Don't go buying no tuxedoes."

Change of Habit is considered to be among Elvis' best films and it has been praised for how it dealt with inner city problems in ways that had never been seen in a Hollywood film. This film was also important in Hollywood history because it was the first film to deal with autism.

Elvis' remaining film appearances were in concert documentaries, which were very successful, although he turned down the leading role in A Star is Born and was working on the karate film, The New Gladiators (film) at the time of his death. Elvis regretted turning down A Star is Born but Change of Habit is said to be the best final film of any singer-turned-actor

This film was Mary Tyler Moore's fourth and final film under her Universal Pictures contract; she did not appear in another theatrical movie until Ordinary People in 1980. Moore and Edward Asner, who also appears in the film playing a police officer, went on to star in The Mary Tyler Moore Show, which premiered in September of the following year. In this film, however, Moore and Asner shared no scenes together.