Terrence Mitchell Riley (born June 24, 1935) is an American composer and performing musician[1] best known as a pioneer of the minimalist school of composition.

[4] Riley later became involved in the experimental San Francisco Tape Music Center, working with Morton Subotnick, Steve Reich, Pauline Oliveros, and Ramon Sender.

His most influential teacher was Pandit Pran Nath (1918–1996), a master of Indian classical voice who also taught La Monte Young, Marian Zazeela, and Michael Harrison.

Its form was an innovation: The piece consists of 53 separate modules of roughly one measure apiece, each containing a different musical pattern but each, as the title implies, in the key of C.[7] One performer beats a steady pulse of Cs on the piano to keep tempo.

In the 1950s Riley was already working with tape loops, a technology still in its infancy at the time; he would later, with the help of a sound engineer, create what he called a "time-lag accumulator".

[8] Premiered in 1968 in the Magic Theatre Exhibition at the Nelson Atkins Gallery in Kansas City,[9] a new version of the installation was commissioned three decades later by Lille 2004-European Capital of Culture and purchased by the Museum of Contemporary Art of Lyon.

[10] In New York City in the mid-1960s he played with his longtime friend La Monte Young, as well as with John Cale and tabla player Angus MacLise, who were founding members of The Velvet Underground.

[11] Charles Hazlewood, in his BBC documentary on Minimalism (Part 1) suggests that the album 'Tubular Bells' by Mike Oldfield was also inspired by Riley's example.

In the liner notes Riley cites Art Tatum, Bud Powell and Bill Evans as his piano "heroes", illustrating the importance of jazz to his conceptions.