The Importance of Being Earnest is a play by Oscar Wilde. It premiered on February 14, 1895 at the St. James's Theatre in London.

Set in England during the late Victorian era, the play's humour derives in part from characters maintaining fictitious identities to allow them to escape unwelcome social obligations. It is also replete with witty dialogue. It has remained Wilde's most popular play to the present day.

The successful opening night of the play marked the climax of Wilde's career, but also heralded his impending downfall. The Marquess of Queensberry, father of Wilde's male lover Lord Alfred Douglas, attempted to enter the theatre that evening, intending to cause a public scandal and expose Wilde's homosexuality. In the event, Wilde was tipped off in advance and Queensberry was refused admission. Nonetheless, Queensberry's hostility to Wilde was soon to trigger the latter's legal travails and eventual imprisonment. Wilde's notoriety caused the play, despite its success, to be closed after only 83 performances. He never wrote another play.