Using a case study of environmental debates about air pollution in Pittsburgh during the late 1960s and early 1970s, James Longhurst examines larger trends in citizen activism outside party politics, linking those trends with the rights revolution of the late twentieth century. He draws upon journalistic accounts, archival documents, legal records, and interviews to explore the actions and arguments of GASP (Group Against Smog and Pollution). This group of environmental activists gained access to political power through claims to citizenship and scientific expertise, supported by the organizational skills, social capital, and maternal rhetoric of middle-class women. Once they gained entry to a newly confrontational policy process, the group engaged in furious public debates over implementation, enforcement, and employment, all amid the decline of Pittsburgh’s industrial economy. The grassroots actions of GASP, and many other groups like it across the nation, show that new developments in policy-making, concepts of citizenship, and the long-standing tradition of middle-class women’s civic activism did more to drive the creation of the modern environmental movement than did changes in environmental philosophy.