The next twenty years of his life were spent at MGM Studios, where he was part of elite group of Hollywood composers. Among the many films that he worked on was the famous 1936 version of "Rose-Marie", starring Jeanette MacDonald and Nelson Eddy. He conducted and wrote songs and scores for the films "The Cuban Love Song", "The Good Earth", "Romeo and Juliet", "Mutiny on the Bounty", "Mrs. Miniver", "The Green Years" and "The Picture of Dorian Gray". His output included the Marx Brothers' "Night at the Opera", the Leo Tolstoy romantic drama "Anna Karenina", two Charles Dickens dramas ("A Tale of Two Cities" and "David Copperfield"), and "Mutiny on the Bounty", which earned him his first Academy Award nomination. He won an Oscar for his musical score for the 1939 film "The Wizard of Oz".