How crowd violence arises and how it spreads: a critical review of theory and evidence

Research on patterns of crowd violence across diverse events (including urban riots, protests, and football crowd ‘disorder’) suggests that shared social identity both specifies appropriate conduct (and hence explains common limits) and is the basis of changes in relations between crowd members and outgroups (hence explaining empowered action and psychological change). Powerful mathematical models have demonstrated that riots influence each other, over and above key predictors such as deprivation. Recent research transcends the concept of ‘contagion’, suggesting instead that pathways of riot diffusion operate through shared identity and collective empowerment.