Every Good Boy Deserves Favour is a stage play by Tom Stoppard with music by André Previn. It was first performed in 1977. The play criticises the Soviet practice of treating political dissidence as a form of mental illness. Its title derives from the popular mnemonic used by music students to remember the notes on the lines of the treble clef. The cast comprises six actors, but also a full orchestra, which not only provides music throughout the play but also forms an essential part of the action. A chamber-orchestra version exists.