The PEGASO project (People for Ecosystem based Governance in Assessing Sustainable development of Ocean and coast) develops an ICZM governance platform which aims at producing integrated assessments in support of policy making decision for the sustainable development of the Mediterranean coastal zone. This paper presents the socio-economic approach developed for the assessment of the "Bouches du Rhone" (France) where conflicting uses and coastal waters pollutions are common management issues. In order to support decision-making, the socio-economic assessment intend to i) identify indicators at appropriate scales, ii) produce a clear overview of socio-economic pressures and associated environmental degradation, iii) analyse the existing links between ecosystem services production and human well-being and iv) underline the cost of management responses. This paper outlines detailed methodological approach developed for this task and the first results obtained in a case study dealing with the analysis of seaside tourism, nautical activities and coastal water quality.