We report on a study on the ways leading teachers in secondary schools use social networks while interacting with their students. We undertook in-depth interviews with five leading teachers, and analyzed logs of interactions in order to identify teaching practices combining social networks. One teacher considerably strengthened her traditional teaching practices to control students according to a pedagogical approach of transmission of knowledge. We found that four teachers fostered social learning, autonomy and active engagement among their students. They thereby fostered the constitution of a learning community – of inquiry, or a moral community, through the use of social network sites. Additionally, we identified the distinctive role of social networks in contributing to the students’ learning to be part of their community.