There continues to be great debate about the desirability of taking actions to limit carbon dioxide (CO2) and other greenhouse gas emissions, but it is important to consider policy instruments that can be employed to meet targets that may eventually be forthcoming. The theoretical advantages of market-based instruments, such as carbon taxes and systems of tradable carbon rights, are striking. In the U.S. domestic context, grandfathered tradable permits will probably be the preferred approach (if any) in the short run, although revenueneutral carbon taxes will hold greater promise in the long run. In the international context, a system of international tradable permits could provide important advantages over alternative approaches, but it is difficult to imagine what existing international institution could administer such a system. Hence, despite the great theoretical advantages of market-based approaches to addressing global climate change, neither domestic political barriers nor international institutional impediments to implementing these and other instruments should be underestimated.