At a middle school in Paris, the Mutuelle Générale de l'Education Nationale (MGEN), in collaboration with the Departmental Directorate for Social Cohesion and the Paris School District, is developing the "Well-being for All at School!" program to ensure that the transition from fifth grade to middle school goes as smoothly as possible for the children. Based in part on training for professionals and community workers, this innovative program brings together professionals and parents around the students. Its unique feature lies in its evaluation at every stage by a researcher collaborating with field workers. Interview with Jérôme Garsi, interventional research fellow at the MGEN Corporate Foundation for Public Health.