Social movement theory attempts to explain the origins, growth, decline, and outcomes of social movements. Current theory builds on several different approaches: European new social movement theory and North American collective behavior, resource mobilization, and political process theories. The field has expanded enormously and made important theoretical advances in the past 30 years. Current theory is at a stage of synthesizing ideas from different approaches, tackling neglected problems, defining scope conditions, and devising new research agendas. Although much social movement theory has been developed through studies of movements in Western countries, research is increasingly conducted in other parts of the world, and theories are beginning to incorporate this work as well as to deal with the globalization of social movements. Key areas of social movement ...