Calls for evidence-based policy often fail to recognise the fundamentally political nature of policy making. Policy makers must identify, evaluate and utilise evidence to solve policy problems in the face of competing priorities and political agendas. Evidence should inform but cannot determine policy choices. This paper draws on theories of "good governance" to develop a framework for analysing and evaluating processes of evidence-informed policy making. "Good governance" requires the use of appropriate bodies of high-quality evidence to inform policy and promotes decision-making processes that are transparent, accountable and open to contestation by the populations they govern.