The Kyoto Protocol is an example of how not to construct a treaty. Negotiators began by focusing on the short term, agreeing that the industrialized countries should cut their emissions of greenhouse gases by about 5% relative to 1990 by 2008–2012. Then they agreed that these cuts should be achieved cost-effectively, incorporating ‘flexible mechanisms’. Only later did they worry about whether the treaty created incentives for broad participation and full compliance. Negotiators should have approached things the other way around. They should have begun by thinking of how they could achieve both broad participation and full compliance, and of how they could reduce emissions in the long term. Had they done so, a better, more effective treaty would have been negotiated. In this essay the author explains why Kyoto is unlikely to succeed in mitigating climate change. He also proposes an alternative treaty design that is likely to work better.