Measured in dollar terms, Hurricane Katrina was the worst natural disaster in American history. Mega-disaster response recovery and mitigation put federalism to an especially difficult test because they require speed, efficiency, decisiveness, and effective coordination. This essay focuses on the response to and recovery from Katrina in order to probe the implications of mega-disasters for federalism. It understands federalism as being composed of four dimensions: the three levels of government and the civic realm. It tests key defenses of federalism against civic and government performance during Katrina. It offers examples of successes and failures involving all four dimensions and provides specific recommendations for improving mega-disaster mitigation, response, and recovery while maintaining an appropriate constitutional balance among the three levels of government and between the civilian government and the military.