 Shortly after graduating from Syracuse, Ingalls began his career as an architect at the firm of Alonzo J. Harriman, Inc., in Auburn, Maine.In 1956 he worked for Engineering Services of Portland, and in 1957 he opened his own private architecture firm, which he continued until retiring in 1995.In a 1989 letter to "The Portland Press Herald", Ingalls wrote, "It is a matter of architectural philosophy to use a few quality exterior materials in a simple way and let the interiors unfold as a series of surprises."