In San Francisco in 1964, the world premiere of Terry Riley's "In C" spawned a movement that literally has changed the face of modern music. "In C" was the first popular piece of what has come to be known as minimalist music, consisting of slowly evolving repetitive patterns. Since then, Riley's compositional style has gone through several incarnations. His contribution to modern music has always been a source of stimulation. On his 50th birthday, KPFA honored this important composer by broadcasting a live performance by the Kronos Quartet featuring all of Riley's music for string quartet, a keyboard performance by the composer himself, and a performance of "In C" which included many of the participants from the 1964 premiere.