After the Cold-War, the European Institutions have to consider the problems of adaptation and adjustment on the one hand, and address the impacts which the Eastern Europe Revolution has evoked on the other. If the Revolution means the rapprochement with the Western Europe and America, then the enlargement and expansion will be a gift the West could offer. This study analyzes the enlargement and expansion of the Organization for Security and Cooperation in Europe (OSCE) and assesses the OSCE's contribution to maintenance of European security.