What is the relationship between the political parties that embrace the democratic process and terrorist groups, which eschew the legal and procedural strictures of democracy? This acclaimed volume provides a detailed theoretical and empirical analysis of this controversial issue. Drawing on a vast array of data, the authors examine a large number of international case studies from Italy, Spain, Lebanon, Turkey, Iran, Israel, Palestine, Peru, Argentina, Japan and Northern Ireland. This comprehensive book is the definitive account of this extremely important subject.