Extensive research has shown that social factors are as important as biological ones in determining health, and their impact is enormous in both adults and children. The challenge of changing public policies and programs remains. Healthier Societies: From Analysis to Action addresses the fundamental questions which will lead the way toward countries investing seriously in improving social conditions, as a way of improving population health. The book is divided into three parts. Section one addresses to what extent health is determined by biological factors, by social factors, and more fundamentally, by the interaction between the two. Section two examines four case studies that demonstrate the ways in which social change can dramatically affect adults’ health, as well as launch children’s lives onto healthy trajectories. This section analyzes the cases of nutrition, working conditions, social inequalities, and geographic disparities. The third section of the book takes a serious look at what would be involved in translating the research findings described throughout the book into action.