A modelling methodology and a tool that supports the analyst in contexts characterized by a multiplicity of actors and information sources and a limited or absent interaction are presented in this paper. In these situations Problem Formulation becomes the first essential aim of a technical intervention applied to acquire, organize, present and reorganize knowledge of the action system, at both an individual and collective level; Model Structuring and Processing are strictly related in the same global approach. The basic structure of a prototype system, designed to assist the analyst in the structuring and then in the “critical reading process”, is also presented.