Existing privacy theories shed light on the mechanisms at work when users decide to share information with an organization – yet do not sufficiently encompass the common practice of sharing user information across organizations. This research study introduces the concept of Interorganizational Information Sharing (IIS) and theorizes on boundary uncertainty and boundary control to develop a model of privacy perceptions in IIS. To empirically validate this model, we collect data through an online survey in the context of smart fitness devices. Our research aims at advancing and articulating the concept of IIS, conceptualizing privacy perceptions based on that understanding, and subsequently relating those perceptions to behavioral intentions to protect privacy in IIS. We thereby contribute to IS privacy literature, considering the complexity of information sharing relationships in a granular manner.