This paper argues that individuals are more likely to have social capital the greater the incidence
of people in their neighborhood who share certain traits which affect the ease and nature of social
interaction. We argue that race and language are examples of such relational traits. The paper
tests this prediction using an indicator of social capital never previously studied: whether
someone uses a carpool to get to work. This measure retains nearly all of the strengths of
previously used measures, and is free of most of their weaknesses. Analysis is conducted on a
merged data set, with individual level data drawn from the 1990 IPUMS Census extract, and
information on neighborhoods (PUMAs) derived from the 1990 Census STF3 tables. The model’s
predictions are confirmed for both race and language.