Questions about the relationship between the environment and international trade have been asked in a variety of different ways, and have yielded a range of answers. This chapter looks at three ways in which the relationship has been studied, and at how each way has developed its own constellation of questions, methods, and epistemologies. It labels the three constellations as the critical, institutionalist, and positivist approaches. The critical approach looks at ways in which globalization, in part through the growth of international trade, can threaten the environment. The institutionalist approach examines the institutions of trade and environmental cooperation with a focus on their legal structures, procedures, and precedents. The positivist approach looks for correlations between the environmental performance of countries and their trade patterns and membership in international trade agreements. The chapter concludes by arguing that scholars can usefully communicate across these approaches more effectively than is often the case.