The dissertation analyzes the emergence of lead contamination in Uruguay as a new political issue at the turn of the millennium. It focuses attention on the formation of an environmental justice movement against lead, and the deployment and interventions of state agencies and professional expertise. As neoliberal restructuring gradually shifted the economy from agro-industry to services over the past two decades, the Uruguayan state and society engaged in a process of "greening" through the proliferation of institutions, laws, discourses and political movements oriented around nature and the environment. The dissertation situates the lead issue between neoliberal fragmentation and social exclusion, on the one hand, and this broader societal "greening" process on the other. It analyzes the origins, dynamics and tensions of neoliberal nature and grassroots environmentalism in Uruguay. The research provides a unique window into the often-neglected environmental dimensions of urban social exclusion, the roots of collective action, and the development and trajectory of emergent ideologies in a little-studied country struggling with a prolonged decline from its once-proud status as the "Switzerland" of South America.