Between 2010 and 2012, the DREAL (Regional Directorate of Environment, Spatial Planning and Housing) and the Prefecture of the Languedoc-Roussillon Region conducted a foresight exercise on the future of the region’s coastal areas to 2050. This article gives an account of that exercise, rooted in a participatory approach led jointly by state bodies and a group of researchers. After a brief reminder of the context in which the exercise was begun, the authors outline the approach followed (choice and prioritization of structural variables, construction of micro- and macro-scenarios). They go on to analyse the participatory and partnership aspects of this approach: relations with the steering committee, shared construction of scenarios, and profiles of the participants. Lastly, they present the findings derived from it through the five scenarios for the future of the Languedoc-Roussillon coastal area to 2050 and the learning-processes and impact of the approach on the participants, as evaluated in a survey of the actors involved carried out after the event, a survey whose findings attest to the highly positive perception of this collaborative foresight approach and of the dynamics it was able to contribute to developing among a certain number of them.