Throughout the first six decades of the twentieth century Alfred Louis Kroeber worked with great distinction as a member of an anthropological circle the ethos of which he could not fully share. His beliefs regarding the evolution of languages, and the controversial notion of cultural evolution more generally, conflicted with the reigning Boasian paradigm. Some of the concepts with which he struggled, such as the familial relationships among American languages and the emergent character of culture, became less problematic after he had passed from the scene. Although Kroeber is regarded as one of the founding figures of American anthropology, his contributions to the establishment of the genetic approach in historical linguistics were overshadowed by the genius of his collaborator and correspondent, Edward Sapir.