This study investigates two types of high schools in South Korea as a social environment for the formation of social capital: selective (foreign language high schools, FLHS) and non-selective (general high schools, GHS). By analyzing in-depth interviews with 22 graduates of FLHS and GHS who attended the same elite university, we found that FLHS generally provide a better social context and students in FLHS are more likely to form ties with their peers than those attending GHS. Furthermore, since FLHS pool the cultural capital owned by individual students, various opportunities for extracurricular activities appear to function as the domain not only for forming social capital but also promoting cultural capital. The results indicate that the friendship ties formed by students from FLHS and GHS have a significant role in organizing their social and academic life at university.