Oklahoma! is the first musical written by the duo of Rodgers and Hammerstein. The musical is based on Lynn Riggs' 1931 play, Green Grow the Lilacs. Set in farm country outside the town of Claremore, Indian Territory, in 1906, it tells the story of farm girl Laurey Williams and her courtship by two rival suitors, cowboy Curly McLain and the sinister and frightening farmhand Jud Fry. A secondary romance concerns cowboy Will Parker and his flirtatious fiancée, Ado Annie.

The original Broadway production opened on March 31, 1943. It was a box office hit and ran for an unprecedented 2,212 performances, later enjoying award-winning revivals, national tours, foreign productions and an Oscar-winning 1955 film adaptation. It has long been a popular choice for school and community productions. Rodgers and Hammerstein won a special Pulitzer Prize for Oklahoma! in 1944.

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. In addition, Oklahoma! features musical themes, or motifs, that recur throughout the work to connect the music and story. A fifteen-minute "dream ballet" reflects Laurey's struggle with her feelings about two men, Curly and Jud.