Introduction

Since the publication of the forerunner of the present book, "Social Capital and Health" edited by Kawachi, Subramanian, and Kim (2008), studies of social capital have continued to expand in new directions, extending into new applications and the analysis of new problems and puzzles in population health. A cursory search of the PubMed database using the search term "Social Capital and Health" reveals that over 2,000 papers were published on the topic in 2011 alone. As we argued in the earlier book, the concept of social capital holds broad appeal in terms of its potential for explaining diverse phenomena in public health. The present chapter defines the concept of social capital for population health research and identifies emerging directions for research on social capital in the global context. We highlight four emerging areas of research: (a) application of social capital to diverse social contexts (e.g., schools, workplaces), (b) understanding the determinants of social capital, (c) strengthening causal inference and developing interventions; and (d) extension of the concept to analyze fresh problems and population subgroups.