Across the world the policing of crowd events remains a salient and ubiquitous social, political and practical issue. This chapter charts the historical contribution of social psychological research and theory to these important concerns. The chapter begins by briefly drawing upon the English riots of August 2011 as the context for considering the chasm that can and does exist between research, policy and practice in this domain. It goes on to explore the evolution of social-identity–based crowd theory in social psychology and its growing influence on police reform both within and beyond the UK across the last four decades. The chapter considers the importance of qualitative analysis, knowledge co-production, ethnography and Participant Action Research as frameworks for promoting effective translation of crowd research into dialogue-based and human-rights–oriented policing practice. The chapter concludes by considering the political challenges and complexities of crossing the researcher–practice divide in this domain and discussing the tensions between dominant metrics of academic performance and the production of highly impactful and socially relevant research.