Oklahoma! is the first musical written by the team of composer Richard Rodgers and librettist Oscar Hammerstein II. The musical is based on Lynn Riggs' 1931 play, Green Grow the Lilacs. Set in Oklahoma Territory outside the town of Claremore in 1906, it tells the story of cowboy Curly McLain and his romance with farm girl Laurey Williams. A secondary romance concerns cowboy Will Parker and his flirtatious fiancée, Ado Annie, a friend of Laurey's.

The original Broadway production opened on March 31, 1943. It was a box-office smash and ran for an unprecedented 2,212 performances, later enjoying award-winning revivals, national tours, foreign productions and an Academy Award-winning 1955 film adaptation. It has long been a popular choice for school and community productions.

This musical, building on the innovations of the earlier Show Boat, epitomized the development of the "book musical", a musical play where the songs and dances are fully integrated into a well-made story with serious dramatic goals that are able to evoke genuine emotions other than laughter.[2] In addition, Oklahoma! features musical themes, or motifs, that recur throughout the work to connect the music and story more closely than any musical ever had before.[3] A fifteen-minute "dream ballet", reflected Laurey's struggle to choose among two men. A special Pulitzer Prize was awarded to Richard Rodgers and Oscar Hammerstein II for Oklahoma! in the category of "Special Awards And Citations – Letters" in 1944.

The film adaptation was directed by Fred Zinnemann and starred Gordon MacRae, Shirley Jones (in her film debut), Rod Steiger, Charlotte Greenwood, Gloria Grahame, Gene Nelson, James Whitmore and Eddie Albert. The production was the first musical directed by Fred Zinnemann.