Williams Mix (1951–1953) is a 4'16" electroacoustic composition by John Cage for eight simultaneously played independent quarter-inch magnetic tapes.

The first piece of octophonic music,[1][2] the piece was created by Cage with the assistance of Earle Brown, Morton Feldman, David Tudor, and Bebe and Louis Barron (who would later create the first all-electronic feature film soundtrack for Forbidden Planet) using many recorded sound sources on tape and a graphic score by the composer.

"Presignifying the development of algorithmic composition, granular synthesis, and sound diffusion," it was the third of five pieces completed in the Project for Music for Magnetic Tape (1951–1954), funded by dedicatee architect Paul F Williams Jr.[3] Richard Kostelanetz of Stereo Review described Williams Mix as a "tape collage composed ... by chance procedures" which, similar to Cage's earlier works (but not many subsequent ones), was "offered to the world in a permanent form.

"[4] The material recorded by the Barrons was organized into six categories: city, country, electronic, manually produced, wind, and "small" sounds.

The work was premiered March 23, 1953 at the University of Illinois Urbana-Champaign as part of an evening that Cage programmed of music for magnetic tape during the Festival of Contemporary Arts.