Interactive social networking sites (SNSs) have transformed information acquisition, communication, and lifestyles. However, the values and sustainability of SNSs largely depend on sustaining users' participation and their willingness to recommend the SNS to others. Research on SNSs has mainly explored the behavioral intentions of users using the social psychology approach. This study integrated the concepts of conformity tendency and perceived playfulness into the technology acceptance model to explain why people continue to use an SNS. We collected 671 valid questionnaires through the SNS site, Facebook, and used a structural equation model to conduct an empirical study. The results indicated that for conformity tendencies, informational influence promoted the continued intention to use SNSs through perceived usefulness, not through normative influence. Furthermore, perceived ease of use was the primary factor that predicted whether users would continue using SNSs, and perceived playfulness may have facilitated users' continued intentions to use SNSs.