Many forms of environmental degradation first increase, then level off and decrease, as national income grows. Does this mean that poor countries have to grow rich before they can improve their environmental performance? In this chapter, I investigate how two domestic factors-a country’s national income and its political system-affect developing countries’ environmental quality alongside four international factors. Unlike most previous studies, which focus solely on a single facet of international integration, such as trade openness or foreign direct investment (FDI), here I build on some of my earlier work and examine whether enlarging the scope of international integration-encompassing membership in international governmental organizations (IOs), international aid, trade openness, and FDI inflows-adds to our understanding of developing countries’ environmental performance.1