In 1891 he became chancellor of Pitt, where he taught anatomy and zoology. In 1901 his friend Andrew Carnegie hired him as director of the Carnegie Museum, where he remained until retirement in 1922. During this time, he achieved international renown when he supervised the mounting of several casts of the sauropod dinosaur Diplodocus, a donation by Carnegie to natural history museums throughout Europe. His trip to Argentina in 1912 to install a replica of a Diplodocus, at the behest of Carnegie, is told by Holland in his 1913 travel book To the River Plate and Back.