Details the West German peace movement's impact on German, U.S., and NATO politics and security dynamics in the 1980s. Why Movements Matter is a provocative account of how the Reagan administration relented to pressures created by international peace movements during one of the most dangerous episodes of the Cold War. Breyman provides the first systematic account of the West German anti-missile movement, among the most important citizen mobilizations of postwar Western history. Contrary to conventional wisdom Breyman offers compelling evidence that peace movements, rather than any escalation of Cold War spending or rhetorical belligerence, hastened the demise of the Cold War. The product of extensive research, Why Movements Matter advances social movement theory and the political sociology of peace movements, expands our understanding of the interaction of political parties and political movements, explores the links between public opinion and organized dissent, and provides an assessment of a movement whose immediate impact shook the halls of power in Washington and Moscow, yet also had a deep and lasting influence on politics, culture, and society.