Social capital is a sociological concept, which refers to the everyday interactions between people and connections between members of groups or networks. Despite its cross disciplinary usefulness, the term social capital remains vaguely and variously defined in scholarly usage (Gonsalves, 2007). Social capital is an attractive and immediately advantageous perspective in trying to understand various processes that occur in societies within changing times. Regardless of the importance of this concept proved by broad scientific research, only few studies have investigated the potential difference in the relationship between bonding versus bridging social capital and school’s impact on them. Drawing upon a research on social and school integration of 12 Polish adolescents from Polish immigrant families residing in Athens, Greece, this study seeks to examine the association between bridging and bonding social capitals and the assumed influence of school on each type of the capital. Following Putnam’s (2000) distinction between bonding and bridging social capital, we utilize social capital as participation in social networks fostered by the school. Presented data consider social capitals relative to 12 Polish adolescents attending schools in Athens, Greece. The general aim of the study that the presented paper is based on focused on addressing the social and school integration of Polish adolescents and also at identifying what fosters these processes for children with an immigrant background. It was a qualitative research relying on semi-structured in-depth interviews with 12 respondents, aged 17 and 18 years old, from Greek and the Polish high schools in Athens, as well as on literature review and text analysis (on social integration, social capital, migrations and adolescence).