This chapter explores how evidence can be used to improve public services, the obstacles to, and facilitators of, improved evidence use and how evidence-informed policy and practice can be encouraged. It argues that evidence can be used to facilitate accountability and to promote improvement in policy-making, programme development and service delivery. It considers three main uses of research for policy and practice, namely to design and develop public policy, to assess the impact of policy intervention and improve policy implementation and to identify tomorrow's issues. It is important to work with inclusive definitions of both evidence and research and to emphasize a 'horses for courses' approach, adapting evidence-gathering approaches to specific policy and practice issues. There is a need for better ongoing interactions between researchers and research users, in long-term partnerships that span the entire research process, from the definition of the problem to the application of findings. However, evidence will and should remain just one of the influences that shape policy development and service delivery.