Einstein on the Beach

Einstein on the Beach is an opera in four acts by Robert Wilson with music composed by Philip Glass. The opera eschews traditional narrative in favor of a formalist approach based on structured spaces laid out by Wilson in a series of storyboards which are framed and connected by five "knee plays" or intermezzos.

The opera's premiere occurred on July 25, 1976, at the Théâtre Municipal in Avignon, France, as part of the Avignon Festival. The opera contains writings by Christopher Knowles, Samuel M. Johnson and Lucinda Childs. It is Glass's first and longest opera score, taking approximately five hours in full performance without intermission; given the length, the audience is permitted to enter and leave as desired.

The work became the first in Glass's thematically related Portrait Trilogy, along with Satyagraha (1979), and Akhnaten (1983). These three operas were described by Glass as portraits of people whose personal vision transformed the thinking of their times through the power of ideas rather than by military force.