This paper analyses some issues raised by Rosa Luxemburg's theory of imperialism that are central to current debates on globalisation. Methodologically, despite widespread scepticism on the use of mathematics in Marxist social science, Luxemburg's rigorous analysis of Marx's schemes of reproduction forcefully shows the importance of theoretical abstraction and formal modelling. Indeed, this paper analyses Luxemburg's theory by means of an intertemporal generalisation of Roemer's (1983) economy with a global capital market. It focuses in particular on two substantive issues: the relation between capital accumulation and imperialism, and the role of force and non-competitive distortions in imperialistic international relations. It argues that differences in development and competitive credit markets, rather than realisation problems, are important to understand the emergence of international exploitation, whereas extra-economic coercion may be important to understand its persistence.