Libraries in the US have a different ethical obligation regarding privacy than do the companies behind the most popular social networking websites. By maintaining a presence on social networking sites, libraries risk legitimizing companies whose primary goal is profit, and whose profit is based on the free flow of information about their customers. This article outlines a model for thinking about these two seemingly contradictory perspectives on privacy. Despite legitimate concerns over privacy, social networking sites are not entirely incompatible with the mission of most libraries. Responsible appropriation of this technology however, requires a nuanced understanding of both libraries commitment to privacy, as well as the nature of the companies that run these websites.