Although grass-roots social movements are an important force of social and political change, they quite often fail to achieve their lofty goals. Similarly, the inability of research to systematically explain the impact of such movements stands in sharp contrast to their emotional appeal. Protest, Opportunities, and Mechanisms attempts to rejuvenate current scholarship by developing a comprehensive theory of social movements and political change. In addition to reviewing the existing literature on the political outcomes of social movements, this volume analyzes the examples of the American civil rights movement and anti-nuclear energy efforts in eighteen countries to forge a new understanding of their momentous impact.