This paper presents a systematic analysis of the results of a participative hands-on training project, focused on occupation accidents prevention, developed since 2006 in a multinational tire production company. Our approach has its grounds within a tradition of work psychology, whose action has been particularly visible in the development of the interdisciplinary project of the "ergonomics of the activity". In close collaboration with local stakeholders and based on recurrent analyses of the work activities at stake, we developed a methodological matrix to approach this problem. We called it "Matriosca" and it also represents the core instrument for the evaluation of the project's results. This paper presents the configuration assumed by the 3rd edition of the project in this company, describing its logic, its characteristics and its evaluation procedures, and some of its results. The results obtained so far contribute to the presentation of a set of principles and tools which potential is advocated. It is in this framework that the effective transformation of the working conditions assumes its protagonism in the reflection developed.
