Despite the worldwide popularity and rapid proliferation of social networking sites (SNS), e.g., Facebook, our understanding about what drive people to SNS and how they use them remains limited. This study aims at establishing a theoretical framework guiding the research on SNS usage. Built upon the Theory of Acceptance and Use of Technology (UTAUT), the framework makes following major extensions: 1) taking a feature-centric perspective in conceptualizing SNS usage; 2) adopting uses and gratifications paradigm to specify the performance expectancies; 3) accounting for the other important social influences (identification and group norms); 4) accounting for the role of anticipated emotions; and 5) accounting for habituation by including prior usage.