 In 1903–04 Cockerell was the curator of the Colorado College Museum; and in 1904 he became lecturer on entomology and in 1906 professor of systematic zoology, at the University of Colorado, where he worked with Junius Henderson in establishing the University of Colorado Museum of Natural History.During World War II he operated the Desert Museum in Palm Springs, California.Cockerell was author of more than 2,200 articles in scientific publications, especially on the Hymenoptera, Hemiptera, and Mollusca, and on paleontology and various phases of evolution, plus some 1700 additional authored works, including treatises on social reform and education.