As global environmental governance evolves, the parties to the 1989 Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal and to the 2001 Stockholm Convention on Persistent Organic Pollutants have established regional centers working on capacity building and technology transfer. This article empirically explores the following questions: Why did the parties to the Basel and Stockholm Conventions establish these regional centers? What roles do the regional centers play in treaty implementation and multilevel governance? The article argues that the parties have set up regional centers in response to three partially overlapping sets of developing- and industrialized-country interests: expanding regional cooperation (both developing and industrialized countries), attracting more resources for treaty implementation (mainly developing countries), and supporting implementation projects across smaller groups of countries (mainly industrialized countries). This article fi...