At age 13, in 1936, Miller became a showgirl at the Bal Tabarin. She was hired as a dancer in the "Black Cat Club" in San Francisco (she reportedly told them she was 18). There, she was discovered by Lucille Ball and talent scout/comic Benny Rubin (although some sources say this occurred at Bal Tabarin). This led Miller to be given a contract with RKO in 1936 at the age of 13 (she had also told them she was 18, and apparently provided a fake birth certificate, procured by her father – with the name "Lucy Ann Collier") and she remained there until 1940. In 1937, she played Ginger Rogers’ dancing partner in Gregory La Cava’s Stage Door. In 1938, she played the quirky, constantly dancing Essie Carmichael in the best-picture Oscar-winner, Frank Capra's You Can't Take it With You, starring Jean Arthur, Lionel Barrymore, Jimmy Stewart and Edward Arnold.