This paper examines international policy options for dealing with the prospect of global climate change. We analyze a number of policies embraced by the Kyoto Protocol (including international trading of emissions permits, "Joint Implementation," and the "Clean Development Mechanism") as well as policies (such as an international carbon tax) not covered by the Protocol. We compare policies in terms of their cost-effectiveness, indicating how international coordination and flexibility can reduce costs of meeting international emissions targets. We also consider issues of fairness and political feasibility associated with different policies. Finally, we explore a number of policy design issues, addressing questions concerning the breadth of policies in terms of nations involved and the greenhouse gases covered.