Hammond's next major discovery was the Count Basie Band, whom he heard on the radio in his car in Chicago, broadcast live from Kansas City one cold January night in '36. The Basie Band was one he "couldn't find any fault with." The band included Hammond's favorite drummer Jo Jones (with "extraordinary wit in his playing"), Lester "Prez" Young on tenor sax, and Jimmy Rushing on vocals. According to Hammond, "Fletcher Henderson started the liberation of the soloist and Basie continued it," per the PBS special.

Hammond's other major discovery in the '30s was Billie Holiday. He first saw her at Monette Moore's club as a substitute singer in '33. She was "17, chubby, quite beautiful. I had never heard anyone sing like that, as though she were the most inspired improviser in the world. She had an uncanny ear, an excellent memory for lyrics, and she sang with an exquisite sense of phrasing..she sang the way Louis Armstrong played horn," wrote Hammond. He followed her from speak-easy to speak-easy in Harlem that year and wrote about her in Melody Maker. He put her together with Teddy Wilson and small combos made up from members of Basie's band.

Hammond capped off his extraordinary decade of the '30s with the Spirituals to Swing concert in late-'38. The concert began with recorded West African music; then boogie woogie pianists Albert Ammons, Meade Lux Lewis and Pete Johnson; blues shouter Big Joe Turner; gospel singer Sister Rosetta Tharpe; blues singer Ruby Smith; pure gospel from Mitchell's Christian Singers; blind harmonica player Sonny Terry; then the New Orleans Dixieland jazz of James P. Johnson, Tommy Ladnier and Sidney Bechet; country blues singer Big Bill Broonzy; and finally, the elegant jazz of the Basie Band with singers Jimmy Rushing and Helen Humes.

Hammond again put his money where his mouth was and invested in New York's first integrated nightclub, Cafe Society, which was a great success for many years featuring many of Hammond's favorite jazz and blues performers.

The '40s were a difficult time for Hammond: his second (of three) son Douglas died, he got divorced, and the onset of be bop alienated him from jazz. He mostly recorded classical music in Europe.

In the late-'50s Goddard Lieberson, who had helped Hammond scout the South for talent for the Spirituals to Swing concert, was president of Columbia and invited Hammond back into the fold. On a songwriters demo tape, Hammond found an 18-year-old Aretha Franklin singing and immediately dubbed her the greatest singer since Billie Holiday. Hammond recorded her with jazz musicians, but Columbia wanted her to record pop and took her away from him. She came into her own on Atlantic where, as Jerry Wexler told Hammond, "We put the church back in her."

According to the PBS special, "Hammond believed that music should be an engine of social change, and looked to the protest songs of the early-'60s to counteract the sentimentality of the '50s." Pete Seeger had been blacklisted as a communist in the '50s, but Hammond brought him to Columbia in the early-'60s. His "We Shall Overcome" became an American standard in '63.