Communities all over the world are using traditional technologies to extract drinkingwater, irrigate their lands and feed their livestock. But these often sustainable and ancient ways to make use of groundwater are in rapid decline worldwide. A research project started in 1999 to study the rehabilitation of 1500-year old water tunnels called "qanats"in Syria. To Cooperate or not to Cooperate...? discusses results and outcomes of this research project. The main objective of this research is to better understand the proces of collective maintenance of these ancient water tunnels. The study evaluates the social, cultural, political and environmental factors that have driven abandonment and decay of qanats in Syria. It tries to reconcile divers theoretical and conceptual frameworks to study collective action with a human ecosystem approach and develop one with a stronger anthropological reference.