Participatory approaches to decision making in water systems planning have gained worldwide a novel significance in integrated water resource management. They are also an important objective of the European Water Framework Directive. This is one of the main reasons that there exists, besides the engineering and natural sciences, a strong call for social science research and expertise to find and facilitate suitable strategies of public involvement and consensus finding. One special area of water systems planning for which this is especially true is the area of river restorations. Large and numerous river restoration projects are currently being carried out throughout Europe and in many other parts of the world. River restorations are today expected to combine improved flood-protection measures with the ecological rehabilitation of the river reaches. This chapter contributes to social science research for new "best practice" in participatory planning of water systems by means of two case studies on river-restoration projects in Switzerland.