Through a study of the Mesoamerican Biological Corridor in Central America and Si-A-Paz, a transboundary protected area in Nicaragua and Costa Rica, the author investigates how a transboundary scale of conservation is enacted. The study shows that in order to meet the conditions of a bioregion, actors involved in transboundary conservation in Central America produced accounts of social and ecological integrity that did not entirely match local narratives. Moreover, transboundary conservation provided actors with increased mobility across governance scales and sources of funding. In turn, this scalar mobility enhanced the power of already powerful actors in the area, helped states to attract international sources of funding, and empowered previously marginalized local groups at the expense of others. The author concludes that actors involved in transboundary conservation attempt to create new meanings of nature and understandings of society in order to produce a new scale of conservation. However, the study highlights the problems of matching discourses of nature to accounts of social unity, and underlines the political nature of scalar projects.