Extremists are people whose ideas or tactics are viewed as outside the mainstream. Looked at this way, extremists are not necessarily twisted or evil. But they can be, especially when they are intolerant and violent. What makes extremists turn violent? This book assumes that extremists are rational: given their ends, they choose the best means to achieve them. The analysis explains why extremist leaders use the tactics they do, and why they are often insensitive to punishment and to loss of life. It also explains how rational people can be motivated to die for the cause. The book covers different aspects of extremism such as revolution, suicide terrorism, and global jihad. The arguments are illustrated with important episodes of extremism, including the French Revolution, the rise of nationalism in Yugoslavia under Milosevic, and the emergence of suicide terror and Al Qaeda today.