Although administrators of online communities (OCs) may focus on improving their OCs through upgrading technology and enhancing the usability of their OCs to attract additional users, the level of OC participation may be associated with social motives. The purpose of this study is to understand how social motivations (that is, network externalities and social norms) affect members committed to OCs. This study tests the hypotheses on data collected from 396 undergraduate students. Data analyses show that network externalities and social norms directly influence social interaction ties, which subsequently results in commitment toward a community. Social norms also directly influence relationship commitments to a community. The results provide insights into how social motivations lead to commitment to an OC, reminding OC administrators to encourage member commitment to the OC from the perspective of social motivations.