This paper aims at defining a dedicated method to analyse existing systems and to implement target models for social and medico-social structures in France. Based on GRAI Method, one proposes generic models for decisional systems and processes. The first application presented here proves that reference models could be used to identify strengths and weaknesses but also specific performance indicators more adapted than existing ones. The main observed results are an improvement of the added value of service and an optimization of strategic management tools. In a second time, we demonstrate that it is necessary to specify reference models for each kind of the 15 structures in order to take into account the people particularisms on one hand and to improve information system to answer efficiently to user needs and institutional requests on the other hand.