Displays are growing in size, and are increasingly deployed in semi-public and public areas. When people use these public displays to pursue personal work, they expose their activities and sensitive data to passers-by. In most cases, such shoulder-surfing by others is likely voyeuristic vs. a deliberate attempt to steal information. Even so, safeguards are needed. Our goal is to mitigate shoulder-surfing problems in such settings. Our method leverages notions of territoriality and proxemics, where we sense and take action based on the spatial relationships between the passerby, the user of the display, and the display itself. First, we provide participants with awareness of shoulder-surfing moments, which in turn helps both parties regulate their behaviours and mediate further social interactions. Second, we provide methods that protect information when shoulder-surfing is detected. Here, users can move or hide information through easy to perform explicit actions. Alternately, the system itself can mask information from the passerby's view when it detects shoulder-surfing moments.