Studied at the Pennsylvania Academy of Fine Arts in Philadelphia under Thomas Eakins. Eakins considered Wallace his favorite student, and by 1881 he had become one of Eakins' assistants at the Academy, holding the position of Chief Demonstrator of Anatomy. During this time, Wallace also posed for many of Eakins' greatest works. He taught at the Art Institute of Chicago and exhibited at the World's Columbian Exposition. Wallace came to Omaha, Nebraska in 1891, as Director of the Western Art Association. Although sometimes unhappy in Omaha, he remained there the rest of his life held by "the bills people owe me and the beauty of the Missouri River Valley."