Abstract: Social capital refers to those features of social relationships-such as levels of interpersonal trust and norms of reciprocity and mutual aid-that facilitate collective action for mutual benefit. Social capital is believed to play an important role in the functioning of community life across a variety of domains, ranging from the prevention of juvenile delinquency and crime, the promotion of successful youth development, and the enhancement of schooling and education to the encouragement of political participation. More recently, researchers have begun to apply the concept to explain variations in health status across geographic localities. In preliminary analyses, the higher the stocks of social capital (as indicated by measures of trust and reciprocity in social surveys), the higher appear to be the health achievement of a given area. Strengthening the social capital within communities may provide an important avenue for reducing socioeconomic disparities in health.