This chapter examines the contribution of Marxism to the study of international relations. It first considers whether globalization is a new phenomenon or a long-standing feature of capitalist development, and whether ‘crisis’ is an inevitable feature of capitalism, and if so, whether capitalism contains the seeds of its own destruction. The chapter proceeds by discussing a number of core features common to Marxist approaches as well as the internationalization of Karl Marx's ideas by Vladimir Lenin and subsequently by writers in the world-system framework. It also explains how Frankfurt School critical theory, and Antonio Gramsci and his various followers, introduced an analysis of culture into Marxist analysis as well as the more recent ‘return to Marx’. Two case studies are presented, one relating to the Naxalite movement in India and the other focusing on the recent experience of Greece. There is also an Opposing Opinions box that asks whether the global economy is the prime determinant of the character of world politics.