As interest in social capital has grown over the past decade—particularly in public health —so has the lack of consensus on exactly what it is and what makes it worth studying. Ichiro Kawachi, a widely respected leader in the field, and 21 contributors (including physicians, economists, and public health experts) discuss the theoretical origins of social capital, the strengths and limitations of current methodologies of measuring it, and salient examples of social capital concepts informing public health practice. Among the highlights: Measurement methods: survey, sociometric, ethnographic, experimental The relationship between social capital and physical health and health behaviors: smoking, substance abuse, physical activity, sexual activity Social capital and mental health: early findings Social capital and the aging community Social capital and disaster preparedness Social Capital and Health is certain to inspire a new generation of research on this topic, and will be of interest to researchers and advanced students in public health, health behavior, and social epidemiology.