This study investigates Facebook users' perceptions of online privacy, exploring their awareness of privacy issues and how their behaviour is influenced by this awareness, as well as the role of trust in an online social networking environment. A cross-sectional survey design is used. The sample frame is a network of Facebook friends; 285 survey responses were collected giving a response rate of 47.5 percent. The study reveals over half of Facebook users have a high level of privacy awareness; however, an element of uncertainty is evident. Privacy concerns are prevalent especially relating to third parties' access to Facebook users' information. Over three-quarters of users have changed their privacy settings to tighter controls, prompted largely by privacy concerns. The most active period for change to privacy settings was 2010, reflecting a response to the controversy surrounding Facebook's privacy approach. Only one-quarter of users trust Facebook, yet the majority of users believe both Facebook and users have an equal obligation to protect users' information.