This expository note provides a critical review of the burgeoning literature on social capital and highlights a number of conceptual and empirical issues. First, the concept of social capital remains largely elusive, with many different ideas attached to it. This elusiveness has serious ramifications for empirical and policy analysis. Second, while the concept of social capital is used to highlight the positive, productive aspects of sociability, it fails in important ways to qualify as a form of capital. Third, there are both theoretical and empirical presumptions that social capital can lead to undesirable socioeconomic outcomes. Finally, a large body of empirical work on social capital remains mired in measurement and estimation problems.