This study aimed to catch a glimpse of teachers' social networks and explore the cause and nature of interaction patterns by using social network analysis. This study was designed as a qualitative case study research. Three high schools from Van, Turkey, were selected with purposeful sampling method and data were collected through semi-structured interviews. Through network and content analyses, it was found that informal interaction networks revealed a form that was different from formal structure. Although each school had a unique network pattern, gender played an important role in relationship patterns in all networks. In addition, similarity of teaching subjects, working duration at school and seniority seemed to bring teachers closer. Finally, it was revealed that teachers who shared common interests had more interactions. All in all, homophily was effective in shaping interactions between teacher dyads.