In celebration of the centennial of the founding of the Peabody Museum of Archaeology and Ethnology at Harvard University, a series of lectures was delivered by five outstanding scholars. These lectures, presented here with an introduction by J. O. Brew, Peabody Professor of American Archaeology and Ethnology and Director of the Peabody Museum, are not simply tributes to the work of the museum, but are a substantial contribution to the history of anthropology over the past one hundred years. F. R. Eggan examines ethnology and social anthropology as they have developed in interaction with their sister disciplines, and with related disciplines in the social sciences and humanities. Gordon Willey sketches the highlights and main trends in the history of American archaeology and shows how, in little more than a hundred years, the primary approaches of the science have swung full circle. Glyn Daniel looks at the advances in old world prehistory—its techniques, and uses of other specialties such as geochronology—and touches upon future problems and possibilities. Floyd Lounsbury describes anthropological linguistics as it was a century ago and traces the progress since then toward answering basic questions. And in conclusion, Sherwood Washburn, discussing the development of biological anthropology, shows how the problems that Darwin raised are now being put into modern form, and considers some of the implications of this transformation.