Recent work by sociologists, geographers and anthropologists has drawn attention to the “de-territorialization” of money, and to the emergence of “alternative” monetary forms such as e-money and complementary currencies. The increasingly diverse nature of these forms raises doubts as to whether “money” is a sufficiently coherent entity to be covered by a single definition. In this paper, these doubts are explored through a critical evaluation of the work of four prominent scholars of money: Cohen, Ingham, Zelizer and Hart. I argue that, despite their empirical richness, these approaches are undermined by a number of conceptual confusions: for example, by a tendency to refer to “money” and “currency” as if they were synonymous. The paper concludes by suggesting that Simmel’s “pure concept” of money provides the most promising basis on which to develop an analytically rigorous treatment of money which can embrace the variety of forms which circulate today.