Communities with high levels of social capital enjoy an array of positive economic and community development outcomes. We assess the role of several key community characteristics, including the strength of government institutions, in explaining local social capital variation. The analysis draws on data from United States counties and includes regression modelling and a Blinder–Oaxaca decomposition to explore differences in social capital across an area’s metropolitan status and region. The data show social capital determinants vary by place both due to the endowment levels of these determinants and the productive value of their coefficients. For example, the coefficient productive values of government capacity explain some differences in social capital levels across metropolitan status (but not across region). Concurrently, variations in government capacity endowment levels help explain some differences in social capital levels across region (but not across metropolitan status).