This text investigates a way to reduce the cost of carbon dioxide and sulphur dioxide emission reduction. It asks whether allowing countries to substitute emission reduction undertaken abroad in lieu of emission reduction at home will reduce the cost of emission reduction and allow more rapid and acute falls in pollution. Analyzing USA Department of Energy data on US emission reduction projects undertaken in Eastern Europe and Central America, the book explains differences in the cost of emission reduction by method and by country. It sets out the conditions that would allow a joint implementation system to evolve into a full-blown tradable permits system. Political and practical objections to joint implementation are aired and addressed. The work is targeted at the environmental policy community, government officials, academics, the NGO community, economists and financiers, members of large corporations and museum educators everywhere.