After leaving agent Irving Mills, he signed on with the William Morris Agency. Mills, though, continued to record Ellington. After only a year, his Master and Variety labels (the small groups had recorded for the latter) collapsed in late 1937. Mills placed Ellington back on Brunswick and those small group units on Vocalion through to 1940. Well-known sides continued to be recorded, "Caravan" in 1937, and "I Let a Song Go Out of My Heart" the following year.
