Couleurs Santé was a community mobilization program implemented in six areas of Brittany, France. The aim of the program was to develop health education projects in schools and among children and adolescents with a view to promoting the development of psychosocial skills and creating healthy environments. Assessment was an integral part of the program, the main aim being to evaluate the effectiveness of the program and its transferability to other settings. The assessment process was examined in order to determine the impact of the assessment on the program and to assess the influence of stakeholders on the assessment method. This paper provides an overview of the development of the program and the associated assessment process and shows how the assessment process has helped to improve the program. The findings highlight the diversity of local approaches and strategies, underlining the importance of the varying interpretations of the initial framework, the contributions of actors and environmental opportunities and constraints. The study also highlights the importance of considering the context and the expectations of actors for developing a method adapted to the program model and for meeting the needs of users.