Beginning in 1914, Sloan taught at the Art Students League, where for the next eighteen years he became a charismatic if eccentric teacher. Sloan also taught briefly at the George Luks Art School. His students respected him for his practical knowledge and integrity, but feared his caustic tongue; as a well-known painter who had nonetheless sold very few paintings, he advised his students, "I have nothing to teach you that will help you to make a living." He disdained careerism among artists and urged his pupils to find joy in the creative process alone.