In Lyon, the Agence Lyon Tranquilité et Médiation (ALTM), an agency of mediation promoted by the municipality, helped to decrease social tension in Gabriel Péri square, which plays a central role for migrant populations in the city. This initiative deploys uniformed mediators to promote long-term social cohesion in a specific and ‘problematic’ area of the city. This state-led intervention exemplifies how social cohesion can be strengthened through a collective, holistic approach that aims at building bridges rather than promoting exclusionary security measures.