The purpose of this study is to identify the pattern of teachers' professional development in virtual social networks. This is a qualitative study conducted using the grounded theory approach. Using criteria sampling, semi-structured interviews were conducted with 15 students. The findings showed that the link between student teachers and the realization of the professional development dimensions is the professional needs of these students. This is because student teachers are self-guided or persuaded by teacher-training university's staff members, including professors and officials, to learn formally and informally from social networks. •The link between student teachers and the realization of the professional development dimensions is the professional needs of these students.•The professional development of student teachers is influenced by content knowledge and educational or pedagogical aspects, which are achieved through the informal use of social networks.•Student teachers spend a lot of time on social networks, so they learn a lot of contents related to their teaching formally and informally.