Initially cast in minor comedic roles as the sexy, innocent young girl, she worked in numerous films for Sennett's studio. In 1919, Sennett cast Prevost in her first lead role in Yankee Doodle in Berlin. The film was a hit and helped to solidify Prevost's career. She scored another success in the 1920 romantic film Love, Honor, and Behave, opposite George O'Hara, another newcomer and Sennett protégé. By 1921, Prevost wanted to move to another studio, later stating that she left Keystone because Sennett was only interested in making money and was unconcerned with creativity. Director King Baggot helped secure her a contract with Universal for $1,000 per week. Prevost was released from her contract with Keystone, and she signed with Universal in 1921.
