Asbl Optim@ leads an experience of participative observation in Seraing since 1998. The complexity of the problems met by the population and the professional division into sectors justified this participative approach. This one concerns the economic, social and human global nature of the territory. It leans on a wide partnership of local actors: professionals, inhabitants and decision-makers. It uses at this end the method of territorial intelligence CATALYSE created by the research team ThéMA-MTI and developed with numerous members of the REIT. The results obtained in terms of interdisciplinary dialogue between inhabitants, professionals and decision-makers; allow identifying axes about the evolution of actors' practices. The CATALYSE method wants to make territorial intelligence tools accessible to territory actors: needs diagnostic, inventory of services, offer and demand confrontation, elaboration of projects, evaluation of individual paths and of collective actions, understanding even production of territorial indicators. It also aspires to respect the "ethical" principles of the sustainable development: citizen participation, global approach and partnership of territory actors. It requires technical skills: data processing and digital edition, data analysis, cartography, etc. It also supposes the appropriation of additional techniques in management and in a new participative frame of animation.