How do the characteristics of your county of residence influence your family’s wealth accumulation over the next ten years? This study examines pre-retirement wealth accumulation during 1989-1999 for families headed by 25 to 54 year olds in 1989. Controlling for individual and family characteristics in 1989, we find that a 1 percentage point increase in the share of county residents with at least a bachelor’s degree is associated with $1,448 in higher 1999 family wealth. This externality of a more educated local population strengthens the case for policies to promote postsecondary education and thus increase the prospects for family wealth-building.