The downfall of the Soviet Union was an unexpected incident, which was neither forecast by Sovietologists nor aimed at by the initiators of perestroika. However, the result of this world historical development was deep changes in international relations; the bipolar world changed to unipolar and the Cold War was over. It is not a surprise that perestroika has inspired widely as well the academic community as the politicians and public to discuss and analyse the political and social processes of the Soviet society, the role of economy, the political and military pressure of President Reagan's administration, and glasnost, not to forget the new foreign policy of Mikhail Gorbachev and Eduard Shevardnadze. In this book, perestroika is approached as an evolutionary process that led to unintended consequences, the breakdown of the Soviet Union. But perestroika and glasnost were transnational processes and consequently they did not have consequences only in the Soviet Union. The common understanding is that, at the least, Prague Spring in 1968, the economic reforms of Hungary and Poland in the 1970s, and the Solidarity opposition movements of eighties in Poland established a strong prehistory of the way to perestroika and new thinking. After perestroika and glasnost were launched by Gorbachev, in particular during its deeper reforms of the late eighties, it had a profound influence on all of Eastern Europe and to some extent on Western Europe. Moreover, we can't understand many features and processes of current Russia if we don't know the history of the Soviet Union. It is obvious that many structural and institutional solutions of current Russia, not to speak of political culture, go back to the Soviet era and the power struggle between President Yeltsin and Parliament in the beginning of nineties. The consequences of perestroika and the legacy of the Soviet Union are discussed in several articles, which also take into account the development of Eastern Europe as an integral part of the Soviet sphere of influence.