Violence and hooliganism at soccer matches nearly doubled from 1973-1977. However, its causes are complex, ranging from lowered societal moral standards and increased public violence to family upbringing. The psychological mechanisms seem to be identification and displacement. Soccer fans imitate the violence they see on the soccer field as they closely identify with their team; anger resulting from unfavorable rulings or events in the game is displaced onto innocent bystanders. Other predisposing factors include use of alcohol, crowd psychology, the importance of the particular match, and press coverage. A survey of 497 hooligans shows that they are almost exclusively male, aged 15-24, and laborers or unskilled workers. About 290 had a history of previous convictions. Hooligans often band together in groups and may commit vandalism and theft before the match, and taunt or attack groups of opposing fans during and especially after matches, when tensions are high. In arresting or ejecting offenders from the soccer grounds, the police act under various legislation, including the Public Order Act of 1936 and the 1964 Police Act. However, the prime responsibility for trouble-free matches rests with the soccer clubs; they may reduce violence by limiting crowd sizes, sectioning off spectator areas to prevent mobs from forming, forbidding the sale of alcoholic beverages, requiring dignified behavior from players, and punishing spectators who disobey grounds regulations. The football association can help these efforts by more strictly disciplining teams that misbehave, and the police can help by keeping good information on past offenders, more strictly patrolling the crowds, and using better methods to detect and control offenders. Contributions the courts and the press can make are also discussed. Tables, related information, and eight references are appended.