AbstractThe paper contains a detailed study of the St. Pauls' riots of April 1980. Particular attention is paid to the limits of participation in the event and the limits of crowd action. It is argued that these limits show clear social form and cannot be explained in terms of the individualistic theories that dominate crowd psychology. Instead a model of crowd behaviour based on the social identity model is advanced to account for the observations. It is concluded that crowd behaviour is more sophisticated and creative than hitherto allowed and that the neglect of this field should be remedied.