Comparative studies have shown the impact of asymmetrical influence between subregionalism and an overriding, usually continental process, the so called ‘hemispheric’ regionalism (Inotai 1997, Phillips 2002, Telò 2001). The EU has become the centre of gravity for European political economy and produces far reaching external integration and cooperation effects among others through its open enlargement process and its strategy of ‘non-dividing’ lines. In searching for the impact of the EU on the Black Sea cooperation process it is important to acknowledge that the complexity and heterogeneity of the region has been matched by a diversity of EU policies and initiatives accordingly. Regional treatment versus differentiation has always been a policy concern at the heart of EU’s eastern approach. EU’s simultaneous adherence to both tools, i.e. regional treatment and differentiation or bilateralism is reflected both in the European Neighbourhood Policy (ENP) as well as in its recent geographical formulations, namely the Black Sea Synergy (BSS) and (EaP).