This study explores emerging approaches to local climate change adaptation planning in the United States and Australia, and seeks to explain why some local authorities have begun to take action despite weak national and state level directives. We compare strategic documents from 13 local authorities across the two nations, representing the “first generation” of adaptation plans. Our focus is on potential explanations for early engagement in adaptation planning – size, location and risk level of the municipality, the existence of national or state mandates and access to supra local resources or support. We also explore the nature and type of adaptation-planning practice emerging and its relationship to climate change mitigation efforts.