This article follows the substantial shift in the position of Karl Marx from a somewhat evolutionist conception of development to one that aligns more with our understanding of combined and uneven development. Lenin’s epistemological break from an orthodox or evolutionist view of development, to a view of the global economy via the hinge of imperialism then ushers in a new view of capitalism as non-homogenous, where part of the world develops and another «under-develops». Does the later neo-Marxist conception of ‘under-development’ represent a continuation of Marx’s concept of capitalist development, or does it represent something completely different? My argument is that we need a return to Marx despite the ambiguities in his own analysis to have a useful guide to development in the 21st Century.