Finian's Rainbow, with music by Burton Lane and lyrics by E.Y. Harburg, was a musical that opened on Broadway in 1947, with Ella Logan and David Wayne in the lead roles. It also featured Sonny Terry onstage, playing harmonica. An odd combination of whimsy, romance, and political satire, the plot revolves around Finian McLonergan, who has escaped from Ireland to the town of Rainbow Valley in the mythical state of Missitucky with his daughter Sharon, intent on burying a stolen pot of gold in the shadows of Fort Knox, in the mistaken belief it will grow and multiply. Hot on their heels is Og, a leprechaun intent on recovering his treasure. Complicating matters are the wishes made by those unknowingly in the vicinity of the hidden crock, and a bombastic senator who makes no effort to conceal his bigotry.
Finian's Rainbow played for 725 performances at the 46th Street Theatre and won three Tony Awards for Orchestra Conductor (a category since discarded), Featured Actor (Wayne), and Choreography.

Although a major success, and despite its recognizable score, the musical rarely is revived due to its outdated view of the racial situation in the American South.

John Hubley was given an offer to make an animated version of the musical, starring the voice talents of Frank Sinatra, Louis Armstrong, and Ella Fitzgerald, but he was blacklisted at the time.

A 1968 film version directed by Francis Ford Coppola starred Fred Astaire as McLonergan, Petula Clark as Sharon, Don Francks as Woody Mahoney, Tommy Steele as Og, Keenan Wynn as the Senator, and Barbara Hancock as Woody's sister, Susan the Silent. Released at a time when the popularity of movie musicals was on the wane, it was dismissed as inconsequential by most critics, who found Astaire's obviously frail and aged appearance shocking (this was his first musical film since Silk Stockings more than a decade earlier) and Steele's manic performance annoying. Highly praised by all was Clark in her American film debut, for which she was nominated for a Best Actress Golden Globe Award, with nominations going to Astaire, Hancock, and the film itself, as well. Although it could have been set in any era, the film did attempt to update some of the song lyric references, with "If this isn't love, I'm Carmen Miranda" becoming "If this isn't love, I'm Zsa Zsa Gabor-a," for example.

The original soundtrack was finally issued on CD in a limited, numbered edition in 2004. The film was released in DVD format on March 15, 2005.

Well-known songs from the musical include "Look to the Rainbow," "How Are Things in Glocca Morra?" (both of which have become staples in Clark's concert repertoire), "Old Devil Moon," "Something Sort of Grandish," and "When I'm Not Near the Girl I Love (I Love the Girl I'm Near)."