This article explores the use of evidence and varieties of knowledge in police decision making. It surveys official government policy, demonstrating that evidence-based policymaking is the dominant policy-making paradigm in the United Kingdom. It discusses the limits to social science knowledge in policymaking. The article explores four ideas associated with the notion of ‘experience’: occupational culture, institutional memory, local knowledge and craft, drawing on data from four UK police forces. We discuss the limits to experiential knowledge and conclude that experience is crucial to evidence-based policing and decision-making because it is the key to weaving the varieties of knowledge together.