This thesis analyzes how the City of Geneva’s Youth Service (SEJ) promotes the inclusion of youth nightlife activities in Geneva’s public spaces. Based on a qualitative study combining observation, interviews, and focus groups with the Service’s professionals, it identifies three areas of action. First, mediation helps manage conflicts of use between young people and local residents through dialogue, negotiation, and the search for compromise, with the aim of reconciling different uses rather than excluding young people from public spaces. Second, promoting harmonious coexistence addresses social perceptions, raises awareness of the realities of youth life, and fosters peaceful coexistence regarding nighttime activities. Finally, the SEJ’s participation in urban planning involves leveraging its expertise in youth practices to anticipate certain tensions, influence development projects, and promote spaces conducive to youth socialization. The thesis also highlights several obstacles to these actions, revealing the tensions between the right to the city, public tranquility, and norms governing the use of nighttime spaces.