While the federal government has been slow to address problems such as climate change, many states have adopted innovative approaches to address the climate impact of using natural resources to produce energy, including aggressive approaches to regulating carbon emissions and renewable and clean energy standards. This Article identifies an emerging challenge that subnational regulation faces in the energy and environmental context -- what I will call maladaptive federalism -- and argues that federalism discussions need to account for its possibility. Part I highlights adaptive regulation as a form of federalism, echoing a vision for subnational regulation many federalism scholars and policymakers have endorsed over the past two decades. Part II argues that policy choices by subnational units of government that fail to account for or consider these coordination benefits should not be celebrated as a form of adaptive federalism merely because they are state policy choices. I identify subnational recalcitrance (on inaction by states) and backlash (or reversing course) as two potential types of maladaptation, provides examples of each, and use these to illustrate the structural features of subnational governments that make maladaptation most likely. Part III argues in favor of pro-adaptation tools that federal agencies can use to address the enactment costs of states taking maladaptive approaches. In certain contexts, focusing on enactment costs associated with the structure of state governments will superior to federal policies that preempt subnational units of government altogether by making the policy choice for them. Such tools not only make maladaptation less likely; they also help to ensure that when a state does opt for an maladaptive policy path that it does so because it is making explicit tradeoffs in ways that are more likely to be welfare-enhancing and politically accountable.