According to the theory of two-level games, negotiators will tailor the agreement at level I so as to be ratifiable at level II in all major countries. This did not happen in the Kyoto negotiations as far as the United States is concerned. We interviewed 27 German, Norwegian, and U.S. participants in and observers to the climate change negotiations regarding their views on three explanations of why the United States did not become a party to the Kyoto Protocol. Explanation 1 argues that delegations in Kyoto mistakenly thought the U.S. Senate was bluffing when adopting the Byrd-Hagel resolution. Explanation 2 contends that the Europeans preferred a more ambitious agreement without the United States to a less ambitious agreement with the United States included. Finally, explanation 3 suggests that in Kyoto the Clinton-Gore administration had already given up on achieving ratification by the Senate, and essentially pushed for an agreement that would provide them with a climate-friendly face. All three explanations received at least some support from people we interviewed. However, explanations 1 and 3 received more support than explanation 2. Moreover, while explanation 1 received most support in Germany and Norway, explanation 3 received most support in the United States. ..PAT.-Unpublished Manuscript [ABSTRACT FROM AUTHOR]