There is widespread evidence of significant gaps between health policies as laid down on paper by governments or ministries of health, and their implementation in practice. As a result, newly proposed and effective health interventions may fail to attain high coverage levels when implemented, and may not fulfil their potential to reduce mortality and morbidity. Various factors enable or constrain the implementation of health policies. These include the content of the policy itself; the actors involved in implementation, and their interests and incentives; the context within which the policies are located; and, the process of policy implementation. Introducing and sustaining equity-orientated health policies, such as increasing access to primary care services or targeting vulnerable groups, has been particularly difficult in many countries. This is because such policies often challenge the conventional ways of working within health systems, including the existing professional practices which influence both who can access health services, and the treatment and nature of care offered to different groups. Despite the evidence of problems, there has been only limited international investigation of the factors which may explain the poor achievements of new policies intended to promote equity. The Consortium for Research on Equitable Health Systems has investigated these factors by examining the experiences of actors involved in implementing policy at different levels of the health system. This document provides summaries of CREHS research relating to health sector reform. Countries involved in the research are: South Africa, Tanzania, Kenya, Thailand, India and Nigeria.