Interdependencies between European countries are well known and strongly documented, but this is not the case for the relations between European regions. This new ESPON project aims at providing a new understanding of the interrelations between Europe’s economies at the regional level. To achieve this goal, this research will use innovative methods to overcome data limitations on interregional linkages and flows of people, goods, capital, knowledge and services. The analysis of the relationships between regions will determine the extent to which the existence and the intensity of interregional flows are drivers for and/or barriers to the development of regional competitiveness and cohesion.