This study proposes and tests a model of online information disclosure to commercial Web sites, which is an important component of e-commerce. Based on social exchange theory and research on self-disclosure in interpersonal contexts, the model emphasizes the role of trust and past online behavior in the disclosure of personal information to a commercial Web site created for this study. Data collected to test the model confirmed all predicted paths. A second aim of this exploratory research was to examine the nature and quality of online disclosure. Data show differences in online information disclosure depending on the characteristics of Internet users and the type of information requested from commercial Web sites.