This article offers a critical review of eight tradable permit markets: water permits at Fox River, Wisconsin; the U.S. leaded gasoline phase-out; sulfur dioxide credits under the U.S. Clean Air Act Amendments of 1990; the Regional Clean Air Incentives Market (RECLAIM) for controlling ozone and acid rain in Southern California; renewable energy credit trading at the regional level in the United States; individual transferrable quotas for fisheries at the national level in New Zealand; carbon credits traded under the European Union-Emissions Trading Scheme; and carbon offsets permitted under the Clean Development Mechanism of the Kyoto Protocol. By "critical" the article does not fully weigh the costs and benefits of each tradable credit [...]