After eight years of non-engagement, the new administration and the U.S. Congress, led by a majority in the President’s party, are rapidly developing climate policy legislation. This paper summarizes past efforts to establish a national climate policy in the United States as well as the major forces influencing the current debate. While this debate is largely shaped by domestic considerations, it takes place as the international community moves to agree on a post-Kyoto policy regime in Copenhagen next December. Whether the United States is willing to take strong action will significantly influence the actions of other nations.