Despite the US rejection of the Kyoto Protocol, the meeting of the parties to the United Nations Framework Convention on Climate Change in July 2001 has increased the likelihood that the Protocol will be ratified. This raises a number of issues concerning mitigation costs, particularly for the buyers and sellers of emission permits. In this paper, we examine how the US decision is likely to affect compliance costs for other Annex B countries during the first commitment period. We also explore the implications for US emissions. Key findings include: