Purpose-Although the impacts of trust on information disclosure have been well recognized, the trust building mechanisms in social media are still underexplored. To fill this gap, the purpose of this paper is to explore two trust building mechanisms, namely, institution-based and transference-based trust building and identify how these two mechanisms vary across gender. Design/methodology/approach-An online survey was conducted to collect data. The partial least squares method was used to examine the relationships among regulatory effectiveness, three trusting perceptions and disclosure intention. A cross-group path coefficient comparison method was used to test gender differences. Findings-The results suggest that regulatory effectiveness affects competence-and character-based trust and these impacts are stronger for males than for females. Both competence-and character-based trust influence general trust in members while their impacts vary. Competence-based trust is more important for males while character-based trust is more important for females. Originality/value-This study contributes to social media literature by identifying the two trust building mechanisms with special attention to the role of regulatory effectiveness and trust transfer. Further, this study also sheds light on how these two mechanisms vary across gender.