Health Impact Assessment (Hia) is a process which helps decision making by predicting the consequences for health of choosing different options in terms of policies, plans, and projects. There is growing interest among health professionals, planners and politicians in using Hia to help safeguard and improve the health of populations and reduce health inequalities.Health Impact Assessment: Past Achievement, Current Understanding, and Future Progress explores the past development of Hia, its current practice and possible future. Written in two parts, the first section by John Kemm provides an overview describing the various ways in which an Hia can be done. Highly practical in emphasis, it describes how Hia can be applied in different contexts to meet the needs of different decision makers and answer a variety of questions. It deals not only with the many good reasons for using Hia but also critically examines the weaknesses of current practice.The second part consists of chapters written by authors practising Hia from different countries throughout the world, demonstrating the various pressures and legislative frameworks that have shaped the evolution of Hia. Illustrating the range of views about the reasons for doing Hia and how it should be done, and revealing how the practice of Hia has been adapted to suit different cultures and help decision making in varying situations.