Alfred Franz Wallenstein was born in Chicago on October 7, 1898. Raised in Los Angeles, he studied music with composer Ferde Grofé's mother, Elsa Johanna Bierlich von Grofé, who was a professional cellist, and with Julius Klengel. Wallenstein joined the San Francisco Symphony as a cellist at age 17, and went on to play cello for the Los Angeles Philharmonic, the Chicago Symphony Orchestra, and the New York Philharmonic under Arturo Toscanini. Toscanini encouraged him to pursue conducting, and his first conducting engagement came as a last-minute substitution at New York radio station WOR, bringing him to the attention of station management. In 1933, WOR began broadcasting the Wallenstein Sinfonietta, and when Toscanini left the New York Philharmonic in 1936, Wallenstein also left, and became the full-time music director at WOR from 1936 until 1943.
As music director, Wallenstein capitalized on the platform to bring a wide range of music to an unprecedented number of radio listeners, both in the New York metropolitan area, on the Mutual radio network, and wherever WOR's clear-channel signal propagated. His coverage was comprehensive, presenting J.S. Bach's cantatas on the Sundays for which they were composed, along with all twenty-six of Mozart's piano concertos, as well as a diverse array of lesser known American composers.
Wallenstein returned to Los Angeles as music director of the Los Angeles Philharmonic in 1943 until 1956, and in 1968 joined the faculty of the Juilliard School of Music, where he became head of the orchestral department in 1971. Alfred Wallenstein died in New York on February 8, 1983.