This chapter summarizes the key findings and discusses the implications of the results for the study of international relations and international trade. It argues that that the decision to enter a preferential trading arrangement (PTA) owes much to domestic politics. Although there are other sources of trade agreements, the domestic political factors uncovered in this study have been vastly neglected. Moreover, the linkages between domestic politics and international institutions, like PTAs, have been underappreciated. Political leaders are highly attuned to their domestic political situation; they take few actions without considering the consequences for domestic politics and their longevity in office. Combining an understanding of their domestic political calculations and their foreign policy behavior may better illuminate the sources of their actions.