Agricultural and urban activities over the last decades have caused an environmental degradation of the social-ecological system of the Mar Menor, compromising the ecosystem services it offers to society. This article describes a stakeholder analysis through a participatory methodology to identify and characterize them, know their preferences about possible management measures and compare their preferences with the preferences expressed by the group of local population to which such actors belong. Results include the identification of seven main stakeholder groups. Despite the discrepancies among them in the preferential order of the management measures, it is important to point out the consensus of all the interviewed actors to prioritize the measure: Reduce the irrigated area to limit the entry of nutrients into the lagoon. This consensus, which is different from the results obtained in previous studies, represents a recent change of opinion regarding the role of agriculture in the Mar Menor. Results also showed that there are discrepancies between the preferences expressed by some stakeholders and the group of population to which such actors belong. From these results, two interesting conclusions emerge regarding the design and implementation of a deliberative participation process: 1) it is possible to foresee difficulties, at least in its initial phase, in reaching possible consensus on the prioritization of measures and 2) the involvement of the identified stakeholders might be positive in such participatory processes, since they present a distance among their respective positions that is less than the one detected among their corresponding sectors in the local population. Therefore, the involvement of these actors in participatory processes can facilitate the generation of consensus that, later, could be extended to their respective sectors.