Despite the UK’s abundance of renewable energy sources and the imperative for renewable energy to make a significant contribution to addressing the problems of climate change and fossil-fuel dependency, renewable energy capacity in the UK has developed slowly compared with some other EU states. The UK has introduced a succession of policies to promote renewable energy, but so far these have failed to meet national and EU targets. This signals the need for detailed examination of the reasons for these ‘failures’ and, in particular, the extent, nature and constraints on ‘policy learning’ within UK renewable energy policy. Policy learning has emerged in recent years as an innovative way of exploring the roles of knowledge acquisition and use in policy change. This study examines the contribution of policy learning to the development of UK renewable energy policy. It is argued that interpreting UK renewable energy policy development through the lens of policy learning yields fresh perspectives on why policies develop in certain directions and not others. In so doing, it critically examines problems caused by failings in policy learning and identifies options for the further promotion of renewable energies in the UK. The study distinguishes four different forms of policy learning: technical, conceptual, social and political. Little research has been conducted on the characteristics of these different learning types, the conditions under which they occur, the psychological, institutional and cultural factors that stimulate or constrain learning, and how they interact to shape policy change. The study utilises a qualitative methodology to analyse and explain changes in UK renewable energy policy over the past 20 years. The main methods employed are content analysis of policy documents (including legislative acts and instruments, consultations and select committee reports); and semi-structured interviews with key stakeholders from government, industry, NGOs, academia and the media. It is argued in the thesis that UK energy policy has tended to become ‘locked’ into low-level forms of technical learning because current government learning mechanisms do not challenge the parameters of existing policy and, thus, fail to stimulate broader processes of conceptual and social learning that might encourage more radical policy change. These forms of policy learning are particularly constrained by hierarchical institutional structures that hinder communication and learning between policy areas. Furthermore, the current style of policy making for renewable energy in the UK privileges the interests of incumbent energy companies, giving them the ability to filter or block new ideas that do not align with their commercial interests. Political learning was shown to operate alongside other types of policy learning and to take multiple forms but focused predominantly on political risk management rather than political innovation: thus, it tended to narrow rather than extend the parameters of debate. These findings were used to develop a model of policy learning in UK renewable energy policy. This was used to conceptualise relationships between different learning types, highlight specific barriers to policy learning, and illustrate dynamics of policy learning and change that might be extended to other policy areas and countries. Finally, it is argued that many of the barriers identified might be overcome by fostering more evidence-based policy making and learning mechanisms that engage with a broader range of stakeholders to stimulate more pluralistic government processes.