In 1924, Lebrun immigrated to the United states to work on commercial artwork in magazines such as Vogue, The New Yorker, and Fortune. He lived in New York until 1930 then studied abroad in Italy focusing on Luca Signorelli's work for 6 years. This led him back to the US to become a mural artist working with a process called fresco. This type of mural painting was the same technique as Diego Rivera. Lebrun created murals for Harvard University (with Lewis Rubenstein under him), New York Post Office, and Pomona College. After his third mural in 1963, he stayed in California and worked with Disney on the production of Bambi. He explained to the artists working on the film to play around with the skeletal structure of deer. The way he drew the deer was still on brand with his stark line contour as seen in Terrified Woman with Child. Looking at these murals and comparing it to his later work, you can see how Lebrun was in development of his own art style. After Bambi, Lebrun gave talks to colleges around the US including Yale, UCLA, Tulane, and Art Students League of NY.