The aim of this paper is to uncover how the patterns of competition and complementarity in the regional system of Italy can explain its persistent internal disparities in spite of cohesion efforts by the European Commission. Our analysis is based on the application of the Dendrinos-Sonis model (1988, 1990) to the Gross Regional Product of the NUTS I regions of Italy over 1951-1993. Essentially, the analysis implies that relative growth in regional income is similar to a zero-sum game in which relative growth in one region takes place at the expense of at least one another. The results show the strong influence of Lombardia on all the regions, and the dominance of complementary relationships over competitive relationships. When the application is extended to industry, non-market services and market services, the nature of the relationships that are revealed raises interesting issues for policies supporting these sectors.