Marxist theory has had a massive influence on medieval economic and social history. Lots of historians, even those who are not Marxist in their politics, have in a sense been historical materialist in their analyses. Marx and Engels themselves, meanwhile, were very interested in the middle ages, in part because of its importance in understanding the transition from feudalism to capitalism. In this paper, Steve Rigby examines seven key Marxist claims that were illustrated by reference to medieval history.