This paper analyzes hooligans: rival football fans bent on brawling. It develops a simple theory of hooligans as rational agents. We model hooligans as persons who derive utility from conflict. Legal penalties for conflicting with non-hooligans drive hooligans to form a kind of ?fight club? where they fight only one another. This club makes it possible for hooligans to realize gains from trade. But it attracts ultra-violent persons we call ?sadists?. If the proportion of fight-club members who are sadists grows sufficiently high, the fight club self-destructs. Rules that regulate the form club conflict can take, but don?t eliminate conflict, can prevent the club from self-destructing even when populated exclusively by sadists. This creates strong pressure for private rules that regulate conflict to emerge within the club. To illustrate our theory we examine the private rules that developed for this purpose among English football hooligans.