This is the concluding part of a three-part article that discusses the transformation of Soviet-East European relations in the late 1980s and the impact of the sweeping changes in Eastern Europe on the Soviet Union. This final segment is divided into two main parts: First, it provides an extended analysis of the bitter public debate that erupted in the Soviet Union in 1990 and 1991 about the “loss” of Eastern Europe and the collapse of the Warsaw Pact. The debate roiled the Soviet political system and fueled the hardline backlash against Mikhail Gorbachev. Second, this part of the article offers a concluding section that highlights the theoretical implications of the article as a whole. The article, as the conclusion shows, sheds light on recent literature concerning the diffusion of political innovations and the external context of democratization and political change.