The United State Supreme Court's holding in Massachusetts v. EPA that greenhouse gases are air pollutants under the Clean Air Act makes it virtually certain that federal climate change legislation will be accomplished by amending that Act. This Article explains and justifies an approach to federal climate legislation that uses and builds on the Act's various tools, including air quality standards, technology-based limitations, and state implementation plans. The Article discusses models for climate response that have emerged from state responses to date and presents the reductions that could be achieved if these were scaled up to the federal level. Federal legislative proposals to date fail to build upon these state lessons and do not provide adequate mechanisms to support the multi-faceted economy wide approach that can achieve needed reductions in a cost-effective manner. We suggest a mechanism whereby the Clean Air Act could be applied or adapted to incorporate state creativity to support the integrated, economy-wide approach that is needed. This approach could also motivate both the individual action and the international cooperation that are required to address climate change effectively.