The past two decades witnessed the international consensus around the idea that health policy decisions should be 'evidence-based'. These efforts have stimulated a wealth of studies explicitly concerned with understanding the use of research evidence in policy. The majority of such studies suggest there are few examples of public health policy outcomes that might reasonably be labelled 'evidence-based'. Only a small number of these studies seek to explore how political dynamics interacted with evidence to shape policy outcomes. Here, we draw on two empirical case studies of efforts to promote public health evidence to decision makers (protection from secondhand smoke in Europe and tackling health inequalities in England), to highlight the primacy of 'policy networks' and 'advocacy' for understanding the role of evidence in achieving policy change. Reflecting on our empirical findings, we argue that the policy networks literature usefully foregrounds the roles that diverse 'policy actors' can play in connecting research and policy. However, our case studies also suggest that popular accounts of policy networks, such as Haas' 'epistemic communities' and Sabatier and Jenkins-Smith's Advocacy Coalition Framework (ACF), overstate the role of core values in driving policy network efforts, while underplaying the role of advocacy, leadership, network communication and trust, scientific consensus, political context and strategic policy trade-offs in network success. We conclude by arguing for further efforts to connect analyses of policy networks and evidence use. We also reflect on the implications of our findings for those seeking to employ evidence to effect policy change.