The authors present a multilevel analysis encompassing institutions and individuals within the government—at national, state, and local levels—as well as the activists, interest groups, and nongovernmental organizations that operate outside formal political channels. They emphasize the importance of networks linking committed actors in the government bureaucracy with activists in civil society. Portraying a gradual process marked by periods of rapid advance, Hochstetler and Keck show how political opportunities have arisen from major political transformations such as the transition to democracy and from critical events, including the well-publicized murders of environmental activists in 1988 and 2004. Rather than view foreign governments and organizations as the instigators of environmental policy change in Brazil, the authors point to their importance at key moments as sources of leverage and support.