For three decades from the mid-1970s, he worked with Barbara Cook as pianist, music director and arranger.
[6] He produced the original cast recordings of those musicals, as well as the Pointer Sisters' revival of Ain't Misbehavin' and Tommy Tune's Slow Dancin'.
Donating his time and experience, Harper served as guest lecturer for the Juilliard School and the Broadway Musical Theatre Project [2] with Tel Aviv University.
He began working with Barbara Cook in the mid-1970s as her musical director, accompanist and arranger.
Together, they created intimate piano-and-voice shows for boites and more lavish orchestral concerts for venues such as Carnegie Hall.