This book is the definitive guide to the topical issue of the relationship between political parties that embrace the democratic process and terrorist groups which eschew the legal and procedural strictures of democracy. The fully revised edition continues to provide the most detailed theoretical and empirical analysis of this controversial issue, highlighting the fluid nature of boundaries between terrorist organisation and legitimate political party. 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. By incorporating substantial new material on ETA, Hizbollah and Hamas, this book retains its position at the forefront of the worldwide political discussion on terrorism, and continues to be essential reading for all students, academics and readers with an interest in security studies, terrorism and political violence.