Web 2.0 technologies have changed the way users interact with the Internet. Users play a growing role in the generation of content, and while doing so disclose a piece of themselves. We seek to provide a theoretical link between the boundary characteristics of a social networking website and self-disclosure. Utilizing Communication Privacy Management Theory, we focus on two forms of boundaries: mode of entry boundary and ingroup/outgroup boundary. We propose that these boundaries play a role in the implicit boundary coordination and negotiation between the users of the environment and the website. This negotiation influences users’ perceived publicness of the environment, which influences their self-disclosure behaviors due to their risk avoidance. It is believed that by recognizing the public aspect of participation in online social networks, we can provide suggestions on how its perception can be managed to encourage, or discourage, contributions and disclosures of information by users.