Peter H. May is professor of agro-food systems and sustainable development in the Graduate Program in Development, Agriculture, and Society at the Federal Rural University, Rio de Janeiro. He is also the executive director of Pro-Natura, an international environment and development organization. He is the coauthor of The Subsidy from Nature(1991) and editor of Natural Resource Valuation and Policy in Brazil(1999), both published by Columbia.Ronaldo Ser�a da Motta is professor of environmental economics at Santa Ursula University, Rio de Janeiro. He is also coordinator of the Center for Environmental Studies at the Institute for Applied Economic Research in the Brazilian Ministry of… Planning, Budget, and Management.