Since the Euro-crisis the cohesion and economic convergence within the EU are questioned from what we derived our exploratory question: “Is there a convergence between the members-states (EU-15) or not?” This will be evaluated within the framework of an empirical analysis. In the first part of our paper we are examining convergence terms and definitions (absolute-, β- and σ- convergence) and their demarcations. Households, companies and nation-states are considered. In the following Gossen’s Law, the Solow model and the principle of subsidiarity are outlined and explained. On this foundation a comparison of the convergence and divergence theories in reality will be drawn.