Cooperation may be defined as the collaboration between two or more parties which fuels initiatives that have shared, or converging interests and objectives. In the European Union territorial cohesion has recently been included in the draft of the European Constitution and is complementary to the EU drive towards economic and social cohesion. This adds a new dimension to European integration which clearly recognises that considering things from a territorial dimension is a tool for reducing the territorial disparity currently present in the EU. In fact, well before its enlargement, significant disparities in prosperity levels existed both between and within member states: prosperity levels in the ten most dynamic regions of the EU, based on GDP per capita, were nearly three times higher than that of the ten least developed regions and regional differences have widened with enlargement. In this context, the territorial cooperation objective aims to: improve cross-border cooperation through joint, local and regional initiatives; strengthen trans-national cooperation by means of actions conducive to integrated territorial development linked to Community priorities as well as to strengthen interregional cooperation and the exchange of experience at the appropriate territorial level. Three different typologies of territorial cooperation have been identified with the European territory: cross-border cooperation, trans-national cooperation and Interregional cooperation. The paper focuses on the territorial cooperation objective and presents a case study with large and strong economic, social and environmental disparities. It includes EU members and non EU members. More specifically, the IPA (Instrument for Pre-Accession Assistance) Adriatic Cross Border Cooperation (CBC) Program, which includes three EU Member States, one Candidate Country, and three Potential Candidates Countries.