This study examined a multilevel model of community loyalty employing social capital atmosphere of group-level as a moderator based on social identity theory. In the theoretical model, community loyalty is predicted by self-categorization, affective commitment, and self-esteem. Meanwhile, each model path is moderated by social capital atmosphere. Empirical model using a survey from the most well-known social networking site in Greater China included 1,101 different responses from 101 groups. The results confirmed all hypotheses in the study. This study is the first to propose a multilevel model of social identity in predicting community loyalty by the cross-level moderating effect of social capital atmosphere.