During the half century leading up to the Second World War, Franz Boas helped to define academic anthropology in the United States. Trained as a geographer at the University of Heidelberg, Boas worked initially on the Inuit of Baffin Island and subsequently on the cultures of the Indians of the Northwest Pacific Coast, becoming a leading figure in American anthropology by the first decade of the twentieth century. As Professor of Anthropology at Columbia University, Boas made significant theoretical contributions to ethnology, linguistics, and physical anthropology, helping to ingrain the four fields approach in his discipline and introducing the concept of cultural relativism into wide currency. He was, as well, a committed Socialist and an ardent opponent of both racism and fascism. This collection includes correspondence that Boas carried on with his colleagues in anthropology, as well as with those in the other social sciences and sciences. This correspondence is rich as a source for twentieth-century historians interested in "radical" social causes, since Boas was a socialist and an outspoken voice for progressive social causes.