To improve access to vaccination and cancer screening, the "13 en santé" project is implementing health mediation initiatives in disadvantaged neighborhoods of Marseille. An evaluation is currently underway to assess the project’s impact by comparing beneficiary neighborhoods with control neighborhoods. While the benefits of health mediation are well-documented, high-level evidence studies are needed for it to be recognized as an “effective intervention.” This approach presents numerous challenges, which are discussed in the first three articles of this report by the key stakeholders: the scientific team, the Provence-Alpes-Côte d’Azur Regional Health Agency (ARS Paca), and the Sept association.