Increasingly, public housing authorities (PHAs) are implementing “no-trespass” policies designed to combat crime by non-residents in their developments. These policies allow PHAs to develop “ban lists” of unwanted non-residents who may be cited for criminal trespass if found on PHA property. Implementation of such policies may conflict with resident’s rights to have visitors, and invitees’ rights to visit. The effects of these policies on crime, perceptions of safety, and associational rights are unknown. Through legal analysis and case studies of three PHAs—Yonkers, NY; Chester, PA; and Annapolis, MD—I investigate the impact of these policies on residents, PHA officials, project managers, police, and people who are banned. My findings suggest that a no-trespass policy, narrowly targeted and as part of a larger security strategy, can promote perceptions of safety among public housing residents. Strong, stable PHA management and a collaborative relationship with residents are key to successful implementation. With due process protections and clear procedures for assuring that tenants’ rights to have visitors are not violated, it can pass constitutional muster. Whether it is an effective, or cost-effective, form of crime control is very much in debate. Implemented in isolation, however, a no-trespass policy is not likely to be effective in reducing crime and promoting perceptions of safety, and runs the risk of being used to police residents, rather than to protect them. If the policy is not narrowly tailored, it can divide families unnecessarily and discourage familial ties that create stability in a community. No-trespass policies can be blunt weapons against crime that cast very wide nets over a community, restrict movement, and interfere with family relationships. Applied arbitrarily and targeted indiscriminately, these policies are not likely to be constitutional. PHAs should consider whether no-trespass policies are worth the considerable resources needed to implement and maintain them, and reassess how these policies fit the larger objective of fostering safe places in which to live and raise a family. Longer-term safety may be better served by developing residents’ human and social capital, and by providing social supports and services, rather than on banning criminals from PHA property.