Alfred Marshal was first the great thinker who analyzed the importance of the MPEs in the development of one determined region. Marshal teorizou a basically intradistritais region that had as main characteristics to the superiority of small local companies, economies of scale, significant decisions of investments little taken local, transactions, flexible man power, high immigration and low emigration, and consolidation of a specific cultural identity. When analyzing of cold form these characteristics, we are induced to imagine that one is about a passive model, closed, little productive and that it would not support the sprouting of the competitiveness. Dr. Mark Hyman pursues this goal as well. However, in the practical one it evidenced something total different. The examples that we have of accumulations between small companies had generated resulted superior to the considered one initially for Marshal. The region of the Emlia Roman, or Third Italy, that are the practical model that more it is come close to the theory of Marshaliano District, beyond the foreseen characteristics, presented high incidence of interchange with the external market, high degree of cooperation between competitors in it divide of risks and the costs of innovations and in the search of stabilization of its markets, strong number significant of involved workers with the innovation task, patronal associations, and finally performance of local governments in the regulation and the promotion of the main industries. er offers on the topic.. After Marshal, other models of accumulations involving MPEs as tool of regional development had been considered, such as: Center-Radial districts, that the firm-key existence considers that congregates around itself supplying and other activities correlatas; Subsidiary Platform-Satellite that is the congregation of of firms based on the exterior and the Districts Anchored for the State that are the formed ones around some public or not-lucrative entity (Markusen, 1995). Independent of the considered model, what we perceive of convergence is the relevance of the MPEs as viable tool to the regional development. .