The OECD Secretariat has developed a multi-region, multi-sector, dynamic applied general equilibrium (AGE) model to quantify the economy-wide and global costs of policies to curb emissions of carbon dioxide (CO2). The project is called the GeneRal Equilibrium ENvironments model, hereafter referred to as GREEN. The purpose of this paper is to provide a full technical description of the GREEN model, its data base and parametrisation as of May 1991. Work is continuing to extend GREEN in several different directions to make the model more policy relevant, and a revised version of the technical manual will be issued in due course ...