Despite a burgeoning debate on substantive issues in IPE, little attention has been devoted to its theoretical foundations. In this important new text, Matthew Watson reviews the main current theoretical approaches to IPE and highlights the problems that arise from treating 'states' and 'markets' as separate and contesting units of analysis. He goes on to show how the more historically informed tradition of 'classical political economy' can provide a firmer basis for analysis of such key substantive issues in IPE as globalization, international trade and development.