In order to provide better marketing services to customers, companies often want to obtain as much customer information as possible. However, for customers, as well as leading to better service, information disclosure may also put them at risk of information leakage, so customers may respond in two different ways to firms’ invitations to disclose information. This paper applies theories of social capital and communication boundary management to developing a framework for understanding the psychological mechanisms behind individuals’ responses to disclosure invitations and their subsequent purchase behavior. The results of this study show that under the combined effect of social capital and communication boundaries, subsequent purchases show an inverted-U-shaped relationship, initially increasing and then decreasing as the level of disclosure increases. Furthermore, because the social capital of high-level members and firms is higher than that of low-level members, it moderates the inverted-U-shaped relationship; that is, the higher the level of membership, the more moderate the inverted-U-shaped relationship.