May 31, 2010, was Quit Facebook Day. But although only around 35,000 of the 500 million Facebook users pledged to quit Facebook on Memorial Day, there's a sense of unease stirring with the social network's strategy. Congress has called for Facebook to explain its stance on the collection and sharing of user information (see epic.org/privacy/facebook), and a spate of high-profile tech experts have given up their accounts following the recent changes to the company's policies. Regular people have also started seriously to weigh the benefits of Facebook against the potentially high cost of loss of privacy. Facebook is an important component of many organizations' outreach and marketing strategies, and it is a forum for professionals to share information and collaborate. Studies have shown that more links are shared via Facebook than any other social tool, including email. As librarians, traditionally staunch guardians of privacy, how can they reconcile their professional ethics with such a new world of openness? The author discusses four major arenas in which libraries and librarians may be involved in Facebook: (1) personal profiles; (2) official library pages; (3) library community pages; and (4) educating patrons. A history of Facebook's privacy settings is also discussed.