In the face of contemporary climate, economic, and social challenges, small municipalities represent a lever that is often underestimated, yet essential for driving systemic change across territories. The international project LE PAPILLON SOURCE, led by Paul Elvere DELSART within the framework of the EL4DEV program, offers a bold alternative by placing these local communities at the heart of ecological and societal transition. Through the sub-program “The Municipalities Counter-Attack,” a groundbreaking model of decentralized cooperation is emerging, giving municipalities with fewer than 5,000 inhabitants the opportunity to become co-owners of strategic infrastructures with high ecological, educational, and economic impact. This initiative is based on shared governance, pooled resources, and a logic of interterritorial solidarity, thereby paving the way for more autonomous, equitable, and resilient development.