This book presents empirical research on the nature and structure of political violence. While most studies of social movements focus on single-nation studies, Donatella della Porta uses a comparative research design to analyze movements in two countries--Italy and Germany--from the 1960s to the 1990s. Through extensive use of official documents and in-depth interviews, della Porta is able to explain the actors' construction of external political reality, and to build a theory on political violence that synthesizes the various interactions among political actors.