▪ Abstract  One of the most salient changes in the world economy since 1980 has been the move toward freer trade among countries across the globe. How do existing theories about trade policy explain this puzzle? Three sets of explanations are prominent. First, many focus on changes in trade policy preferences among domestic actors, either societal groups or political leaders. Second, scholars examine changes in political institutions to account for such policy change. Third, they seek explanations in changes in the international political system. Large-scale changes in political institutions, especially in the direction of democracy, may be necessary for the kind of massive trade liberalization that has occurred. But changes in preferences cannot be overlooked in explaining the rush to free trade. Moreover, the influence of international institutions has been important. Finally, the reciprocal impact of trade on domestic politics and the international political system is important. If the rush to free trade is sustained, will its impact be benign or malign?