The management of large common-pool resources, like fisheries and forests, is more difficult when more people and more communities can access them—a particular problem given increased population sizes and higher mobility in the Anthropocene. Social relationships spanning communities, such as kin relationships, business or trade relationships, and friendships, can make management even more challenging by facilitating overharvesting, transmitting norms for overharvesting, and encouraging corruption. However, these long-distance relationships can also bolster management by transmitting norms for sustainability, promoting interdependence, and laying the groundwork for nested management systems. Here, we review the positive and negative impacts of long-distance relationships on natural resource management, providing illustrative examples from our field research on forest and fisheries management in Tanzania. Drawing on the evolutionary literature, the development literature, and our field data, we offer suggestions for how development partners may leverage, or even deliberately foster long-distance relationships to promote successful natural resource management.