The organizational interface remains a little studied object. The research suggests investigating it and understanding the dynamics.The first part clarifies the foundations of the research. Having defined the interface, il creates that the instability of the interfaces results from imbalance in the processes of integration-differentiation. To measure these phenomena, the methodology appeals to two methods: the elaboration and the analysis of a base of verbatim, and a research-intervention.The second part is dedicated to the determiners of the object. She specifies the properties and the activities of the interface, and proposes a modelling. A crossed analysis of 14 interfaces is then explained; three determiners of the regulation in the interface are identified: the degree of uncertainty, the frequency of the interactions and the distribution of the power. On these bases, a typology of the interfaces is proposed: strategic, political, of coordination, and social.The third part deepens the research by the in vivo observation and the transformation of the interfaces. It brings to light their costs of functioning, the fundamental role of their finalization, and shows that the processes of integration and differentiation ask the question of their quality, besides that of their intensity. The hypothesis according to which the piloting of the organizational interfaces improves the équilibration of the integration-differentiation is discussed then experimented. From the first results of experiment, the research identifies levers of piloting of the interfaces and formula of the managerial implications.