This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book considers the implications of Max Weber's social theory for an understanding of social movements, supplemented by the work of Robert Michels. The origins of the social movement are thus intertwined with the rise of modernity itself. The confluence of capitalism, state building, urbanization, proletarianization, and warfare provided the networks, resources, identities, and grievances for social movements. The rise of the social movement marked a qualitative shift in collective action as people intervened repeatedly in national affairs to pursue new claims through large-scale coordinated action. Sparked by the civil rights movement in the United States and anticolonial struggles abroad, movements came to be seen by many as legitimate and justifiable challenges to political regimes in need of major transformation.