 Copland chose Boulanger to be his composition instructor, and he became leader of the composition department at Tanglewood.Leonard Bernstein, who worked closely with Caldwell at Tanglewood in the 1950s, and became a close friend of Copland's in the 1930s, became a mentor to JoAnn Falletta.It was at Tanglewood that Goldovsky let Caldwell substitute conduct for him when he was hospitalized for an illness in the early postwar era.