During the last twenty years, the introduction of the principle of subsidiarity and the identification of regions as political entities for the coordination of structural expenditure at the local level have led to the adoption of the principle of multi-level governance (MLG), on which principle EU government action is still based. The principle is based on the notion that the spread of governing practices (governance) across various institutions, and hence jurisdictions, results in a greater efficiency of allocation and an improved regulatory capacity compared to what more centralized governmental models are capable of yelding. According to this view, multi-level forms of government are better able to identify the effects of external economies which arise from the supply of public goods at different territorial levels. In other words, a multi-level governmental model enables, more so than other models, these external economies to be internalized and, at the same time, complex and heterogeneous demand from the local populations to be met through territorial intervention policies. Within this framework we will describe the multi level governance (MLG) model adopted from all the Countries of the EU, which constitutes the basis for national and local Public Administrations’ actions in the field of the social and economic development policy addressed to the disadvantaged areas of the Communitarian territory. We will present: a theoretical description of the model MLG in its different categories; the category adopted as a target by the EU with its specific characteristics, and the way those characteristics determine, in terms of operating consequences, the definition of objectives, responsibilities and roles. With reference to the Italian case, we will also describe the practical effects of the MLG model both on the communitarian and national funds governance.