The predictive relations between social capital depth (high-quality relationships across contexts) and breadth (friendship network extensivity) and early-adult life adjustment outcomes were examined using data from a prospective longitudinal study. Interviews at age 22 yielded (a) psychometrically sound indexes of relationship quality with parents, peers, and romantic partners that served as indicators of a latent construct of social capital depth, and (b) a measure of number of close friends. In follow-up interviews at age 24, participants reported on their behavioral adjustment, educational attainment, and arrests and illicit substance use. Early-adolescent assessments of behavioral adjustment and academic performance served as controls; data on what were construed as interpersonal assets (teacher-rated social skills) and opportunities (family income) were also collected at this time. Results showed that depth was associated with overall better young-adult adjustment, net of prior adjustment, and assets and opportunities. Breadth was only modestly associated with later outcomes, and when its overlap with depth was taken into account, breadth predicted higher levels of subsequent externalizing problems. These findings are consistent with the notion that social capital is multidimensional and that elements of it confer distinct benefits during an important life transition. (Contains 3 tables.)