Understanding the impact of research on policy is a vital, and often overlooked, element of policy-making. A systematic literature review was conducted to examine methods for evaluating the impact of research on policy outcomes. The review focused in particular on strategic policy levels (rather than implementation) and waste, environment and pollution policy. The review draws on an international literature, although it is limited to English language publications. The findings identify the different methods used, the advantages and disadvantages of different approaches and the methods that are most effective (particularly in terms of cost). The field of research impact evaluation is currently experiencing rapid development, and there is scope to develop and apply new conceptual frameworks and innovative methods for evaluation, and to conduct and publish more research impact evaluations.