ABSTRACT
Governments and other organisations across the western world are increasingly investing in complex initiatives aimed at tackling the social ills of their societies. But growing enthusiasm for addressing such problems is rarely matched by sufficient thought about the design and implementation of interventions. The chapter describes how theory-based approach has informed the national evaluation of Health Action Zones in England. Substantial efforts were made by the evaluation team and the Department of Health to persuade local stakeholders of the practical value of the approach. The knowledge gap requires the development of new approaches to learning about effective methods of intervening to promote a more equitable distribution of health opportunities. Health policy has been through many different phases. Immediately after the Second World War most countries gave priority to promoting universal coverage for health care. Carefully designed studies with well-defined interventions can generate very powerful learning about the health consequences of different course of actions.
