Since the last decade of XIX century outlines of conventional type prevailed in Europe like alternative to the dicothomy open market/protetionism, becoming a model of mediation among legitimate national interests as well as a support of an economic and social model of Europe. At first, europeans tried the way of bilateral understandings among States, making mutual concessions and elaborating commercial treaties. Afterwards, the sphere of their intervention was broadened to the social field through the debates and the plans that carried to the establishment of the Labour office in Basel, in the beginning of the century. This essay tries to analyze the debates which were basilar in order to establish this conventional model inside the League of the Nations and the other international foundations, above all at the end of the Twenties, when a model of partial integration was elaborated. That model, both regional and progressive, would have had a great importance to define the european identity after the second world war.