This is a case study on a small mountainous island in the Aegean Sea with the policy goal of preparing it to become member of UNESCO’s World Network of Biosphere Reserves. While the local community opted for such an identity very early on, there are a number of obstacles to be overcome. The multidisciplinary research is based upon a sociometabolic approach and focuses on two issues: The transformation of agriculture, mainly herding of sheep and goats, and the shift to tourism. The degradation of the landscape caused by extensive roaming of goats and sheep constitute one of the major sustainability challenges of the island. We analyze farmers’ opportunities and describe new initiatives to get out of this deadlock. The impacts of the transition to tourism are addressed from an infrastructural perspective: A shift from traditional stone buildings to bricks and concrete, the establishment of new roads and ports, and the challenges to water supply and wastewater removal, also with reference to the quality and amounts of wastes generated that need to be dealt with. The island has so far escaped mass tourism and attracts mainly eco-tourists who value its remoteness and wilderness. We discuss how to serve this clientele best in the future, and increase local job opportunities and income while maintaining environmental quality. Finally, we reflect upon emerging new forms of local collaboration and the impact of our research efforts on a sustainability transition that might be on its way.