Maas first began working on silent films in 1920, when he created the scenario for Uncle Sam of Freedom Ridge. After settling in Hollywood, he would continue to make live in Los Angeles his whole life.
It was not until 1926 when Maas would write the entire script, beginning to end, for a movie, The Country Beyond. In 1927 he worked on the successful movie The Way of All Flesh, but it went uncredited.
In Hollywood, he also married fellow screenwriter Frederica Sagor Maas, who became a famous Silent-era writer and Hollywood personality. The last film he wrote was with his wife, the 1947 landmark The Shocking Miss Pilgrim. Being uninterested in adapting to talking pictures, Maas never made or contributed to a film again. The couple lived together until his death in Los Angeles.