The Society of Evidence-Based Policing is a worldwide movement aiming to professionalise policing from within. This chapter charts its origins and explores what EBP means in practice. The partnership between the Mayor’s Office for Policing and Crime and the Metropolitan Police is discussed in relation to tackling violent crime and teenage homicide. The benefits of a joint youth violence profile that provided the platform for evidence-based interventions are highlighted. The governance of EBP is explored in the context of London, and, finally, the challenges and opportunities facing EBP are described. These include fragility, hierarchy, the methods war, technology, and politicians.