Effectiveness of participation in environmental governance is a proliferating assertion in literature that is also reflected in European legislation, such as the European Water Framework Directive (WFD). The Directive mandates participatory river basin management planning across the EU aiming at the delivery of better policy outputs and enhanced implementation. Yet, the impact of this planning mode in WFD implementation remains unclear, though the first planning phase was completed in 2009 and the first implementation cycle by the end of 2015. Notwithstanding the expanding body of literature on WFD implementation, a rather scattered single case study approach seems to predominate. This paper reports on implementation of the WFD in three case studies from Germany, Spain and the United Kingdom, reflecting three substantially different approaches to participatory river basin management planning, on the basis of a comparative case study design. We ask if and how participation improved the environmental standard of outputs and the quality of implementation. We found an increasing quality of outputs with increasing intensity of local participation. Further, social outcomes such as learning occurred within dialogical settings, whereas empowerment and network building emerged also in the case characterized mainly by one-way information. Finally, one important finding deviant from the literature is that stakeholder acceptance seems to be more related to processes than to outputs.