The construct of social capital has recently captured the interest of researchers in social epidemiology and public health. The authors review current hypotheses on the social capital and health link, and examine the empirical evidence and its implications for health policy. The construct of social capital employed in the public health literature lacks depth compared with its uses in social science. It presents itself as an alternative to materialist structural inequalities (class, gender, and race) and invokes a romanticized view of communities without social conflict that favors an idealist psychology over a psychology connected to material resources and social structure. The evidence on social capital as a determinant of better health is scant or ambiguous. Even if confirmed, such hypotheses call for attention to social determinants beyond the proximal realm of individualized sociopsychological infrastructure. Social capital is used in public health as an alternative to both state-centered economic redistribution and party politics, and represents a potential privatization of both economics and politics. Such uses of social capital mirror recent "third way" policies in Germany, the United Kingdom, and United States. If third way policies lose support in Europe, the prominence of social capital there might be short lived. In the United States, where the working class is less likely to influence social policy, interest in social capital could be longer lived or could drift into academic limbo like other psychosocial constructs once heralded as the next big idea.