This article was inspired by an important number of empirical studies on regional performances, studies which on the one hand classify the Ile de France Region as a high performing entity in terms of productivity, and on the other hand, as an entity which does not exploit its full potential (relatively weak growth). This leads us to interpret such contrasting data in terms of adaptability subjected to the constraints of the productive system of Paris and its suburbs. One explanation put forward is the existence of a lack of coordination due, among other things, to the density and to the highly complex nature of this metropolitan area. On an analytical plane, one has to call into question the approach which links performances to structures. There isn?t necessarily interaction linked to geographical proximity which is implicitly the hypothesis of such a model. We suggest a return to the mechanisms of microeconomics.