This paper examines voting by members of Congress on three trade bills introduced in 1993 and 1994: the North American Free Trade Agreement (NAFTA), the agreements concluded in the Uruguay Round of multilateral trade negotiations (GATT), and most-favored nation status for China. We first review recent political economy models of trade policy and then presenting a brief legislative history of the three bills, use these models to formulate an empirical specification of political behavior. In our empirical tests, we find evidence that campaign contributions given be political action committees influenced legislators' votes on both the NAFTA and GATT bills. Contributions from labor groups were associated with votes against freer trade, while contributions from business groups were associated with votes in favor of freer trade. We also find that the broad policy views of the legislators, industry employment in each member's state or congressional district, and general economic conditions in the district or state affected voting on the trade bills.