News reports of the latest atrocity by political extremists are often explained as extreme acts by unbalanced individuals who bear little resemblance to the 'normal' people around us. This book warns that this explanation - though satisfying - is an over-simplification which does not help us to understand why individuals use violence to achieve political ends. The author adopts and interdisciplinary approach to help define the concept of fanaticism, understand how individual behaviour is controlled, and identifies the three elements in an ideology likely to result in violent expression: the Milennarian promise of a utopian future, an emphasis on the role of the individual in attaining the perfect future state, and the absence of public space - an indvidual's access to broader social and political discussion and opinion. The book discusses fanaticism in groups as diverse as the Bader-Meinhof Gang, the Ku Klux Klan and the suffragette movement. The closing chapter discusses the My Lai massacre and underlines the ability of ordinary individuals to commit extreme and violent acts in extraordinary circumstances.