In an increasingly complex world of interrelated problems many governments have tried to modernise their institutional structures and the ways in which they go about making policy. In the UK and elsewhere this has been most apparent in the growing emphasis given to evidence-based policy making in contrast to faith-based approaches and the conviction politics of earlier periods. Much of the debate about the impact and indeed value of this apparently new approach has focussed on the supply side of the equation: on the utilisation of research evidence and how researchers might make their work more relevant and useful to policy makers. Less attention has been paid in these debates to the different ways in which the nature of policy and policy making is conceptualised and how this might affect the relationship between research and policy. This article takes forward this debate by critically reviewing the theorisation of the policy/ research relationship under three different conceptions of policy making: the stages model, the advocacy coalition framework and the argumentative turn. It considers the future of policy research via two questions: who should carry out policy research in which settings; and what skills do they need to do so more effectively?