To provide a context for the unique speed and extent of the contagion in 1391, a number of previous outbreaks of anti-Jewish violence are explored, in the Holy Roman Empire, England and Iberia, assessing, in each case, the dynamics of the outbreaks, agencies that both provoked and limited the spread of violence, evidence on the motivations and behaviour of the crowds involved and the official response. The main context in most cases was provided by crusade and epidemic disease but other social and political factors were evidently at work.