What are the determinants of the formation of the Black Sea Economic Cooperation (BSEC)? This is the question around which this dissertation evolves. Simple it might be as a question, preoccupation with it aims at disclosing the substance and nature of contemporary subregional cooperation which takes place at the borderlands of Europe. This dissertation is above all a case study based on empirical research. The object of analysis is the Black Sea Economic Cooperation (BSEC), a cooperative structure that emerged in Europe in the early 1990s. Here we do not claim to undertake an area research rather we aim at examining an international political economy phenomenon. The main conceptual element of this dissertation is that it brings forward the notion of subregionalism. To examine the formation of Black Sea subregionalism we embark on an eclectic theoretical approach and apply an analytical framework of five variables which come both from within the subregional level and outside of it: economic difficulties, transnational demands, leadership, security dilemma and the European Union. What this dissertation concludes is that BSEC is an intergovernmental mode of cooperation representing more a foreign policy tool and less an integration process. We show that the Black Sea has witnessed a structural or 'instrumental' subregionalism of intergovernmental nature which is shaped by the interplay of the above mentioned variables. The correlation between subregionalism (around the Black Sea) and regionalism (Europe-wide) is thus of great importance. Thus, BSEC is better understood not within the framework of the regionalization-globalization nexus but rather in the framework of the new European order. Furthermore we show how contemporary subregionalism, being a primarily political instrument, is of a flexible nature responding to different needs at different times.