What is the relationship between social capital and democracy? Some scholars, followingTocqueville, argue that social capital is an important precondition to democracy (Inglehart 1997;Putnam 1993). Others argue that social capital is in fact “endogenous” to democratic institutions(Jackman and Miller 1998). This paper explores a third possibility, often acknowledged but notyet tested empirically: a reciprocal relationship between social capital and democracy. Drawingon the 1990-93 World Values Survey and a variety of other cross-national data, I first presentevidence that democracy and social capital are related at the bivariate level, and that thisrelationship persists in more fully specified models. I then estimate a structural equations model,allowing for a reciprocal linkage between interpersonal trust and the quality of democracy inparticular. The results indicate a degree of reciprocity, although democracy’s impact on socialtrust is much greater than social trust’s impact on democracy. Thus these results also providesome confirmation of the endogeneity thesis.