He wrote most of the music for films produced by Walt Disney, such as Snow White and the Seven Dwarfs, Dumbo, Bambi, The Adventures of Ichabod and Mr. Toad, and Peter Pan.
After dropping out of medical studies at UCLA to pursue a career in music, he became an accompanist at the Los Angeles radio station KNX (AM) in 1924.
He joined Disney studios in 1930, and scored many animated shorts - his song for The Three Little Pigs, "Who's Afraid of the Big Bad Wolf", was a huge commercial success.
In 1937, he was chosen to score Disney's first full-length animated feature, Snow White and the Seven Dwarfs with Paul Smith and Leigh Harline.
His catchy, artfully written songs played a large part in the film's initial success and continuing popularity.