Rainger examines how and why vertebrate paleontology, a relatively marginal field of scientific inquiry, flourished at New York’s American Museum of Natural History in the early 20th century. It focuses on Henry Fairfield Osborn (1857-1935), a prominent scientist and administrator who dominated vertebrate paleontology in that era and played a pivotal role in creating a leading institution and a manor program of research in that field. Born into a wealthy New York family, Osborn was in a unique position to follow vigorously his scientific interests in vertebrate paleontology and further worldwide science education through use of the considerable social, political, and financial resources at his command. Yet he was able to guide the development of the American Museum of Natural History’s program in vertebrate paleontology in such a manner as to avoid conflict with the values and beliefs associated with the interests of the upper-class elite who supported the program. His ties to a wide network of influential figures, including the trustees of the American Museum, provided him with the political and financial resources necessary to build a major program in vertebrate paleontology. An ambitious and energetic man, Osborn took advantage of those opportunities to promote his field of study and to establish himself as a leading administrator at the American Museum, Colombia University, and the New York Zoological Society.