In 2001, President George W. Bush confirmed that the US would not ratify the Kyoto Protocol. Despite the US' withdrawal, its neighbor Canada chose to ratify the Kyoto Protocol the following year. The divergence of these two highly integrated countries is surprising, since Canada and the US accepted comparable commitments in the 1997 Kyoto negotiations, and both could expect the costs of compliance to be significant given the greenhouse-gas intensive nature of their economies. The divergence cannot be explained by politicians' electoral incentives since Canadian and US politicians alike faced strong business opposition and a relatively inattentive public. A strong normative commitment to international cooperation to protect the global commons was necessary to overcome political opposition to ratification, but still not sufficient. In particular, while both Canadian Prime Minister Jean Chrétien and US President Bill Clinton supported ratification, only Chrétien had the institutional capacity to deliver on his values.