With growing recognition of the social determinants of health, social capital is an increasingly important concept in international health research. Although there is relatively little experience of measuring social capital, particularly in developing countries, there are now a number of studies that allow the identification of some key issues that need to be considered when measuring social capital. After summarizing definitions and the rise of interest in the link between social capital and health, measures used in key studies of social capital and health are presented. Some important issues are then considered: obtaining a sufficiently comprehensive measure which empirically captures the latest theoretical developments in the field (particularly the concepts of cognitive, structural, bonding and bridging social capital); moving from the individual to the ecological level; consideration of confounding factors, and validity and reliability.