To study phenomena like communication, migration, epidemics, and trade is to study diffusion. In social and cultural anthropology, the systematic study of cultural diffusion emerged in contradistinction to speculations about humanity’s cultural evolution from primitive origins to a state of civilization. The research of diffusion has been a constant in anthropology ever since, although the designations for the topics of this research have shifted. This article presents key topics in the anthropological study of cultural diffusion, including acculturation, world system, globalization, and the social life of things.