In introducing this Special Issue on Social Capital and Health, this article tracks the popularization of the term and sheds light on the controversy surrounding the term and its definitions. It sets out four mechanisms that link social capital with health: making information available to community members, impacting social norms, enhancing the health care services and their accessibility in a community, and offering psychosocial support networks. Approaches to the measurement of social capital include the Social Capital Community Benchmark Survey (SCCBS) developed by Robert Putnam, and the Petris Social Capital Index (PSCI), which looks at community voluntary organizations using public data available for the entire United States. The article defines community social capital (CSC) as the extent and density of trust, cooperation, and associational links and activity within a given population. Four articles on CSC are introduced in two categories: those that address behaviors -- particularly utilization of health services and use of tobacco, alcohol, and drugs; and those that look at links between social capital and physical or mental health. Policy implications include: funding and/or tax subsidies that would support the creation of social capital; laws and regulations; and generation of enthusiasm among communities and leaders to develop social capital. The next steps in the research programme are to continue testing the mechanisms; to look for natural experiments; and to find better public policies to foster social capital.