Scholars debate whether cultural capital reproduces existing inequalities or provides a path to upward mobility. Most studies, however, focus only on cross-sectional associations and are unclear about how disadvantaged adolescents can increase their amounts of cultural capital. Adolescents may be able to increase cultural capital through ties to adults with high educational attainment.We investigate this topic using experimental longitudinal data on mentoring relationships. We find that mentors with a college degree or greater have positive effects on cultural capital, but primarily for adolescents with a parent with some college or greater. Thus, cultural capital may not be an engine of social mobility if adolescents from low-SES households cannot obtain or increase their cultural capital.