Cultural capital is influential in determining who continues on to and succeeds in higher education. However, scholars debate whether cultural capital serves to reproduce existing inequalities or provide a path to upward mobility. Most quantitative studies focus on point-in-time correlations between cultural capital measures and educational achievement or attainment. Thus, this work is unclear on how or even if disadvantaged adolescents can significantly increase their stores of cultural capital. One potential way of providing adolescents with an opportunity to gain cultural capital is through ties to adults with high educational attainment. We investigate this topic using unique quasi-experimental longitudinal data on mentoring relationships between adolescents and adults in the Big Brothers/Big Sisters of America program. We find that only mentors with a college degree or greater have positive effects on cultural capital for adolescents. Furthermore, most of the effects of social capital on cultural capital hold only for adolescents with a parent with some college or greater. We question whether cultural capital can truly be an engine of social mobility if adolescents from low-SES households cannot obtain or increase their cultural capital.