Born Irwin Michnick and graduating from Yale (1951 Bachelor of Music, 1952 Master of Music) under Paul Hindemith, he began as a jazz musician and writing commercials for radio and television. In 1965 he teamed up with lyricist Joe Darion and writer Dale Wasserman to write a musical based on Wasserman's 1959 television play, I, Don Quixote. The resulting show, Man Of La Mancha opened on Broadway and ran for 2,328 performances.
Also composed the jingle: "Nobody Doesn't Like Sara Lee"