Politics has of course never been carried out in fully closed domestic arenas. Yet most observers agree that globalization during recent decades has been an important trend in the system of international relations. Countries are to begin with economically interdependent, and increasingly so. The expansion of international broadcast media, and the growing importance of intergovernmental organizations, also implies that national systems of government are becoming increasingly interdependent politically. Global ideas diffuse across country borders. Decision-making power in previously domestic affairs is being transferred to new government bodies in the international arena. Last, but not least, countries intervene intentionally in the domestic politics of one another.

There are thus various reasons to believe that international determinants played a key role in the third wave of democratization. But did they? In this chapter, I address this question after reviewing the extant literature on international determinants of democratization. My results speak in favor of there being three non-domestic forces at work: international trade, neighbor diffusion and pressure from regional international organizations. By again consulting both statistical and case study evidence, I then aim to uncover the mechanisms responsible for these results.