Welcome to the National Adaptive Capacity Framework, or NAC! NAC represents a new way of thinking about adaptation planning and evaluation, which is being designed by the World Resources Institute (WRI) in consultation with a wide range of adaptation experts and stakeholders. Under the NAC approach, adaptation is treated as an organic process one which inevitably will grow and evolve in unexpected ways, since every country has a unique set of actors who play different roles in adaptation. NAC views the institutional relationships between these actors as an adaptation system that can support ongoing adaptation by communities, businesses, government agencies, and others much as ecological relationships support the well-being of organisms in an ecosystem.