Even though users have become increasingly concerned about their privacy online, they continue to disclose deeply personal information in a number of online venues, including e-commerce portals and social networking sites. Scholars have tried to explain this inconsistency between attitudes and behavior by suggesting that online users consciously weigh the trade-off between the costs and benefits of online information disclosure. We argue that online user behaviors are not always rational, but may occur due to expedient decision-making in the heat of the moment. Such decisions are based on cognitive heuristics (i.e., rules of thumb) rather than on a careful analysis of each transaction. Based on this premise, we seek to identify the specific triggers for disclosure of private information online. In the experiment reported here, we explore the operation of two specific heuristics—benefit and fuzzy boundary—in influencing privacy-related attitudes and behaviors. Theoretical and design implications are discussed.