President Clinton's failure to gain renewal of fast-track authority in 1997 means that further trade liberalization for the United States is likely to slow down significantly or grind to a halt, since negotiators in other countries know that any agreements reached could be modified by the US Congress. This political impasse raises several overarching questions: does congressional rejection of the president's request for fast-track authority represent a temporary or permanent setback in the steady postwar movement toward freer trade?; was its failure to pass due simply to lax efforts in mobilizing groups that support trade liberalization, or is US trade policy moving toward greater protectionism?; and more generally, what were the most important economic and social factors shaping congressional voting behaviour on trade legislation in the 1990s and how do these factors differ among the various trade bills considered by Congress over this period? Baldwin and Magee attempt to answer these questions by analyzing four key trade bills: NAFTA (1993); the Uruguay Round agreements (1994); most favoured nation treatment for China (1993); and the extension of fast-track authority (1997-98). The authors provide a brief legislative history of each of the bills and outline the methodology used in their analysis. They give special attention to the role of campaign contributions in influencing voting decisions because of recent concerns in Congress and elsewhere about the undesirable effects of those contributions and their importance in the voting models of economists and political scientists.