Advances in digital networked communication technology over the last two decades have brought the issue of personal privacy into sharper focus within contemporary public discourse. In this dissertation, I explain the Fourth Amendment and the role that privacy expectations play in the constitutional protection of personal privacy generally, and then narrow the focus on this issue to the context of social networking sites. For the legal protection of personal privacy under the Fourth Amendment, a person must have what courts term "a reasonable expectation of privacy." For an expectation of privacy in a given context to be deemed reasonable, society must consider that expectation as reasonable, yet no empirical research has explored what society would consider to be a reasonable expectation of privacy in online contexts. I argue that in order to make decisions about societal privacy expectations, judges should rely on social science data to determine what society considers as being reasonable expectations of privacy within any given context, including online. I further argue that by using social science theories of privacy and protection, it is possible to predict people's privacy expectations in online contexts. More specifically, I suggest that based on research on privacy in various social science disciplines, people's normative expectations of privacy depend on what information they think is observable in specific situations. Findings from this study support the notion that people have lower expectations of privacy when they believe their information to be more readily observable, and the results highlight the complicated nature of privacy expectations in the social networking context in particular. A model was proposed in this dissertation to explore how people's privacy expectations differ depending on the audience for their personal information, and it was found that within the context of social networking sites, the factors that contribute to different types of privacy expectations (i.e., the privacy expectations surrounding different potential audiences for one's information) vary widely. That is, some privacy protection behaviors (implementing privacy settings) influence privacy expectations about the degree to which other social networking site (SNS) users should have access to one's personal information, whereas other privacy protection behaviors (reading a site's privacy policies) affect privacy expectations regarding what information people expect law enforcement officers to have access to in SNSs. Similarly, the factors that were hypothesized in the model to influence privacy protection behaviors, including for example, past experience using SNS, personality, and demographic variables, functioned differently depending on the type of privacy expectation. Implications of these results for law and policy are discussed, as are avenues for future research to investigate the role of privacy expectations in the broader privacy literature, both offline and online. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]