Since the commissioning of the ‘El Cabril’ Central Storage Facility for Low- and Intermediate-level Radioactive Waste (hereafter ‘El Cabril’), most people living in nearby towns and villages have regarded this nuclear facility with a marked degree of rejection and distrust. This study examines the process of analysis, management and intervention specifically designed and implemented with a view to mediating in the socio-environmental conflict in the host village and neighbouring communities. It vindicates the use of participatory action research (PAR) as the most appropriate methodology for this self-compositional process of conflict resolution, in which this university research team acted as an impartial extrajudicial mediator in a context marked by opposing interests.