Why do people riot? From the Boston Massacre in 1770 to the Los Angeles riots of 1992, mob violence in the United States is often sparked by unjust court decisions, unfair taxes, unpopular wars, the fear of unemployment, and racial and ethnic prejudice. But there are also seemingly senseless riots over wild concerts and sports championships. What causes a peacefully assembled crowd to turn into a mindless, violent mob? What causes a police force or militia to lose control? In this timely, comprehensive overview, Jules Archer describes and explains the causes of mob violence in the United States and suggests that unless we make some basic changes in the nature of our society, the despair and rage that ignite mob violence may always be with us.