Born in Colfax, California, Riley studied at Shasta College, San Francisco State University. He was involved in the experimental San Francisco Tape Music Center working with Morton Subotnick, Steve Reich, Pauline Oliveros and Ramon Sender. His most influential teacher, however, was Pandit Pran Nath (1918-1996), a master of Indian classical voice, who also taught La Monte Young and Marian Zazeela. Riley made numerous trips to India over the course of their association to study and to accompany him on tabla, tambura, and voice. Throughout the 1960s he traveled frequently around Europe as well, taking in musical influences and supporting himself by playing in piano bars, until he joined the Mills College faculty in 1971 to teach Indian classical music.