This case study is made from an action-research intervention in a very huge multinational company of telecommunications. The objectives of the projects were to change the miond (attitudes, behavior and competences) of all these people who work in software development in the company (several thousands of persons). This intervention has been done during the 2009 year. The results of our work that we have capitalized and shared with the top managers of the company are to our mind interesting enough to be published in a scientific symposium like ERIMA. The genesis of the project is first presented as far as it is central to understand the very nature of the complex process that has been developed. Then, the way we have organized and implemented our intervention will be explained. The idea of an insufficient preparation of the intervention (idea well shared by participants, managers, animators, researchers) will be discussed in the light of the results we have obtained. After a reflection of capitalization (done with the managers of the company), we think and they have written that the results we have obtained are interesting and that they constitute a good basis for a generalization of the change process.Read less <