Henryk Grossman’s discussion of economic crises was designed to complement his Leninist understanding of politics. For Grossman, as for Marx, the fundamental contradiction of capitalist production is between the unlimited scope for expanding the output of use values and restrictions imposed by the framework of producing profits. The increasing weight of capitalists’ outlays on dead compared to living labour, which is the only source of new value, gives rise to the system’s tendency to break down and hence to economic crises. Deep financial crises can only be understood in the context of developments in production and particularly movements in the rate of profit. The initial widespread hostility to Grossman’s development of Marxist economics can mainly be explained in terms of the logics of social democratic and Stalinist politics. In contrast to dominant views on the left today, the Marxist tradition in which Grossman stood places the construction of organisations capable of assisting the working class’s conquest of political power at the heart of the responsibility of socialists. Grossman’s political practice expressed his understanding of the close relationship between capitalism’s breakdown tendency and the importance of building a revolutionary party.