The association Santé environnement pour tous (Sept), which has been working to reduce health inequalities since 2019, is leading the "Médiation 13" health initiative in the northern neighborhoods of Marseille. Its efforts aim to improve cancer screening and vaccination rates among a population that is underserved by the healthcare system. The ongoing evaluation requires the team of mediators to constantly reassess their approach, regularly rethinking their methods to adapt to the realities on the ground.