Capitalism has undoubtedly been a central preoccupation-in some ways the central preoccupation-of post-eighteenth century social theory. I have chosen here to interrogate the idea of capitalism through a detailed examination of the writings of the two men who were by common consent its greatest social theorists, Karl Marx and Max Weber. Capitalism is also approached from a particular standpoint: the degree to which its analysis is able to ground a sociology of modernity, understood as ‘that which is “new” in “modern” society’. This nicely tautological definition, which I gratefully borrow from David Frisby (1985:1), leaves open the question of just what this novelty comprises. Marx and Weber offer one kind of answer, to which capitalism, in different ways, is quite central. There have, of course, been others, above all those of Durkheim and Simmel. These contributions receive some attention here too, though much less than they deserve. I also try to connect, where relevant, with the concerns of more recent writers, notably Foucault. My main aim in this book, however, is to provide a clear account-if sometimes a critical one-of the sociology of capitalism and modernity developed by Marx and Weber themselves. It remains, I believe, supremely relevant to understanding the world in which we live.