Sol Tax (30 October 1907 – 4 January 1995) was an American anthropologist. He is best known for his studies of the Meskwaki, or Fox, Indians, for "action-anthropological" research titled the Fox Project, and for founding the academic journal Current Anthropology. He received his doctorate from the University of Chicago in 1935.

Tax grew up in Milwaukee, Wisconsin. During his formative years he was involved in a number of social clubs. Among these was the Newsboys Republic with which his first encounter was when he was "arrested" for breaking their rules. Tax began his undergraduate education at the University of Chicago but had to leave for lack of funds. He returned to school at the University of Wisconsin, Madison, where he studied with Ralph Linton. He was also heavily influenced by the University of Chicago anthropologist Fred Eggan, in whose footsteps he followed in attempting to integrate principles of social anthropology to the study of Native Americans. He later taught at the University of Chicago.

He was the main organizer for the 1959 Darwin Centennial Celebration held at the University of Chicago.

The American Anthropological Association presented to him and Bela Maday its Franz Boas award for exemplary service to anthropology in 1977. He was the association's president in 1959.

The term penny capitalism was first used in 1953 to describe indigenous economies in which there is land tenure over tiny plots of land, where farmers produce crop surplus and engage in small-scale trading. Microfinance evolved in penny capitalist economies.