Mary Lou was a superb pianist and important arranger. Her style blended boogie-woogie and swing. A child prodigy, at 13 she was working vaudeville shows. By 19 she was the pianist and arranger for the incredibly popular Andy Kirk band. She was one of the first women in jazz who truly crossed gender lines.
Mary Lou also wrote arrangements for Benny Goodman, Earl Hines and Tommy Dorsey. Some of her more famous songs were 'Walkin' and Swingin',' 'Little Joe From Chicago' and 'Satchel-Mout Baby.' Mary Lou also worked with Duke Ellington and Dizzy Gillespie. In 1954 she left the jazz world to become a Catholic, returning a few years later. Towards the end of her life she taught at Duke University, which hosts the Mary Lou Williams Center for Black Culture.