Schools are social institutions where students and young people spend a significant part of their lives. Social capital in an institutional structure is based on the connections within the community involved in this structure. The strong and intense nature of these relationships makes it possible to construct social capital. Therefore, the success of many institutions is hidden in the close relations that their employees establish with each other and the school a principal play a key role in establishing and maintaining these relations. In this study, the process of building social capital elements of the school principals with a central and key role in schools and how it reflects on the school environment are examined and the effect of this reflection on the success of the school has been examined. As regards, this study focused on how school principals were creating an environment of mutual trust, the establishment of a network of social relations between the individuals in the school (manager-teacher-student-parent, etc.) and the presentation of social environments where school staff and students and parents can come together and how to build such a sense of belonging and to cooperate with the school as the indicators of social capital. The research was conducted within the context of qualitative research by using semi-structured interview technique in Trabzon. Ten school principals working in different school types in the city center of Trabzon were included in the study. Within the scope of the research, a descriptive study was carried out in order to allow comparison between different school types from secondary schools in Trabzon. In this context, it was determined that reflecting the social capital elements built by the efforts of school administrators contributed positively to the success of the school.