The relationship between international evidence, politics and policy is never straightforward. Politicians sometimes cite comparative findings from social science evidence collected and analysed by international organisations to support policy proposals without sufficient understanding of contextual factors. The media may exploit data from such studies to highlight national policy successes and failures. Academic literature on evidence-based policy is often more interested in identifying policies that work than in investigating the reasons why policy solutions might, or might not, be effective if transferred to other regions. This article explores some of the issues involved by examining the relationship between evidence producers and users in different institutional settings, drawing on case studies in health and social policy to illuminate the complexities of the policy process. In considering possible conditions for successful policy learning across time and space, the authors stress the critical need to take account of socioeconomic, political, cultural and disciplinary contexts.