[3] During the 1930s, except for one year with the Ray Noble orchestra,[4] he was studio musician for CBS Radio, and was the resident hot trombonist on the network's popular jam session The Saturday Night Swing Club.

Vocalists included Terry Allen, Carlotta Dale, Lynn Gardner, Steve Jordan, Ray McKinley, Phyllis Myles, Larry Southern, and Jimmy Valentine.

The latter song was recorded by the Will Bradley Trio (McKinley on drums, Slack on piano, and Doc Goldberg on bass), with the vocal by songwriter Don Raye.

He remained in demand as a recording-studio musician; in the mid-forties he recorded as "Will Bradley and His Boogie Woogie Boys," and he filmed more Soundies in 1944, leading a nine-piece combo.

In December 1954 he signed with NBC Radio's flagship station in New York, WRCA, joining many veterans of the big-band era to provide live music on the air.