Today,users share large amounts of information about themselves on their online social networks. Besides the intended information, this sharing process often also “leaks” sensitive information about the users - and by proxy - about their peers. This study investigates the effect of awareness about such leakage of information on user behavior. In particular, taking inspiration from “second-hand smoke” campaigns, this study creates “social awareness” campaign where users are reminded of the information they are leaking about themselves and their friends. The results indicate that the number of users disallowing the access per- missions doubles with the social awareness campaign as compared to a baseline method. The findings are useful for system designers considering privacy as a holistic social challenge rather than a purely technical issue.