中文摘要：

社交网络服务（SNS）用户的活跃行为对社交网站的成功以及社会化商务的发展都至关重要。本研究集成承诺理论、社会支持理论、沉没成本理论和社会影响理论，实证研究了决定用户总体活跃行为的心智模式以及影响这些心智模式的环境因素。通过对1239位人人网用户的数据收集和分析，模型结果显示，情感承诺和持续承诺是决定SNS用户总体活跃行为的主要心智模式，情感支持和信息支持构建情感承诺，声誉资本和关系资本构建持续承诺，社会规范和从众构建规范承诺。研究结果扩展了相关理论应用，丰富了SNS领域研究视角，并对业界有指导意义。

英文摘要：

While users＇ active behavior is important for the survival of social network services （SNSs） and the success of social commerce, hardly any extant research has explored the mind-sets driving users＇ active behavior and the antecedents determining these mindsets in the SNS context. Because SNS users are the primary human resources who co-produce and generate the excitement and services that determine the level of traffic to the community, users often act as ＂partial employees＂ of online communities. Thus, Originated from the organization behavior domain, commitment theory is appropriate to explain users＇ mind-sets of active behavior in a SNS. In addition, social support theory, sunk cost theory, and social influence theory can be considered as antecedents determining three components of commitment （i.e., affective, continuance, and normative commit- ment） respectively. In this study, we developed a research model by integrating commitment theory, social support, sunk cost theory, and the social influence perspective to investigate the mind-sets driving users＇ active behavior and antecedents of these mind-sets. The results of our survey of 1239 users of Renren in China indicated that affective and continuance commitments are the main drivers of users＇ active behavior on SNSs, while normative commitment has little influence on users＇ active behavior. Further, informational support and emotional support from the social support theory, reputational capital and relational capital from the sunk cost theory, subjective norm and perceived critical mass from the social influence perspective perform well as antecedents of affective, continuance, and normative commitment, respectively. Taken together, these findings contribute to the SNS literature and deepen our understanding about user＇s active behavior in a SNS. This study extends the application of the commitment theory and proves the different roles of three components of commitment in driving user＇s active behavior. The integrating