This paper studies the effect of online social networking functions on user participation with data collected from a Chinese online community. Leveraging on an exogenous change to the social networking function, we use a differences-in-differences approach to identify the effect of role identity salience on user participation. A formal theoretical model is proposed to investigate the equilibrium participation and friend network usage behavior. Predictions made from our theoretical model are confirmed by our empirical results. We also check the robustness of our result for different model settings and sub-samples. This research contributes to the IS literature about user participation in online communities. We extend previous literature by introducing another factor, role-identity, from the social economics literature, and empirically testing its significance with observational data. In this way, our research also contributes to the recent literature on empirical social economics.