Introduction: Data show the relevance of a comprehensive approach to health promotion to support children in developing health skills. Health-promoting holistic interventional researches are complex. The Alliance for health aims to enact and assess the impact of a comprehensive approach to health promotion at the school and community levels. This is an intersectoral project involving regional education authorities, regional public health agency, local policy makers, researchers, and local health promotion operators. Methods: This project involves 101 French primary schools and 97 associated municipalities in the AURA region randomly selected in an intervention and control groups. From September 2019 to June 2022, the intervention was implemented in the intervention group. Primary school teachers were provided training, support, and resources to develop a health-promoting environment in school according to the Health-Promoting Schools framework. Meanwhile, school deputies and territorial agents involved in extracurricular activities were provided training, support, and resources in the same aim. Intersectoral working sessions were promoted. From September 2022 to June 2023, the intervention is implemented in the control group. Quantitative and qualitative data regarding indicators and processes were collected to evaluate the intervention in both groups before implementation, in spring 2021 and spring 2022. This abstract focuses on implementation outcomes based on semi-structured interviews conducted in Spring 2022. Results: Our sample included 11 district pedagogical advisors, 10 school principals, 9 school deputies, 2 extracurricular agents, 1 person in charge of after-school programs and 1 health promotion project manager. Schools’ perspective. Identified facilitators were constant and available referral, institutional support and dedicated time, aim and issues clear from the beginning, support from the community, multi-school training sessions, contextualized support. Barriers were COVID-pandemic, lack of community support, lack of time. Community perspective. Identified facilitators were health promotion perceived legitimacy, collective motivation, regular and effective working sessions. Barriers were perceived methodological incompetence, administrative burden, lack of time. Conclusions: Collective work dynamics, practices’ exchanges, health promotion professional identity are essential implementation components. Lack of time is perceived as a structural barrier. Communities pointed out perceived legitimacy and competences as corner-stones of their engagement. These interesting outcomes are to be confronted to data collected in the control group in spring 2023.