Governments are seeking to improve evidence-based policy making as well as trust in decision-making processes. This report offers a first global mapping of principles for the good governance of evidence in policy making, as well as standards of evidence from a significant range of OECD countries and international research bodies. Reflecting both the nature of existing practices and the various facets that contribute to quality evidence, the report takes stock of the full range of considerations involved in providing evidence across the policy cycle when designing public sector interventions, especially in the social policy area. The report also represents a first step in identifying and developing guidance at the international level in the area of evidence and evaluation.