Shortly after he became Chairman of the Department of Radiology in July, 1975, Stanley Baum expressed interest in a departmental history to Francis James Dallett, Archivist of the University of Pennsylvania. Mr. Dallett passed that information on to me, and I began my research in December of that year. Dr. Baum's enthusiasm for the project and the willingness of current and former staff members to speak with me made the work possible. Eugene P. Pendergrass, M.D., was especially cooperative in answering my questions and passing along materials from his files. Their encouragement, plus that of Robert M. Stein, Associate Dean of the School of Medicine, then Department Administrator, permitted me to investigate the department's history at length. I presented two lectures to the department's staff on my research: "The Department before World War I" on May 27, 1976, and "The Pendergrass Era" on September 22, 1976. A first draft of the manuscript covering the period through Dr. Pendergrass's chairmanship was completed in the fall of 1976, but it has taken me until now to revise and complete the work. My full-time position as an Assistant Curator at Independence National Historical Park has kept me busy, and I would not have been able to complete the project yet, were it not for the professional support and understanding of my supervisor, John C. Milley, Chief, Division of Museum Operations.