A critical question in public policy is how governments bring about change in society. Policymakers around the world wrestle with this question, and how governments work with and mobilise other actors to be able to effect change. The limited range of formal powers available to national policymakers in Wales means that this challenge is both more complex and acute. The WCPP’s work in this area looks at the role of evidence in effective policy making, and how to develop policies that can be delivered.