Discussions of policy networks are becoming increasingly common in the analysis of public policy in, for instance, the UK, Europe and the USA. However, while there is general agreement that policy networks exist (operating as links between actors within a particular policy domain) there is much less agreement as to the explanatory utility of the concept or the broader significance of the growth of networks. This text addresses the key theoretical questions and pursues the central issue of whether policy networks affect policy outcomes. It examines the utility of the policy network approach by presenting a series of comparative case studies which explore for example: how networks change; the significance of interpersonal (as compared with structural) links within a network; whether certain groups dominate the network; and what methods are appropriate to study policy networks.