Public participation in environmental governance is widely believed to produce more environmentally sustainable policy outcomes than less participatory forms of governance. Scholarly literature and current (European) public policy assume that public participation leads to better-informed decisions, collective learning and a stronger consideration of ‘ecological’ values, as well as higher levels of acceptance and compliance. Participation is thereby expected to lead to ‘better’ environmental outcomes. However, the benefits of participation are disputed on theoretical as well as empirical grounds. While there is much faith in the merits of participatory environmental governance, evidence is lacking. The ‘EDGE’ project – Evaluating the Delivery of Environmental Governance using an Evidence-based Research Design – employs an innovative mixed methods approach, with the aim of substantially improving our knowledge on what works in environmental governance.

The paper outlines a framework for conceptualising the relationship between decision-making processes, policy outputs, social and environmental outcomes, and concrete environmental impacts. We then describe our three-pronged approach, which combines: (1) Development of a theoretically-informed analytical coding scheme, applied to a large-N case survey meta-analysis (Yin & Heald 1975; Larsson 1993) of documented cases of environmental decision-making, designed for high external validity; (2) A novel field experimental design, responding to calls for the extension of this approach in political science (Gerber & Green 2002), for the investigation of citizen participation in EU governance processes (in the context of EU Floods Directive implementation), and designed for high internal validity, and; (3) A retrospective case study approach to analysing citizen engagement in participatory planning (in the context of EU Water Framework Directive implementation). We expect that our findings will significantly advance scientific understanding of the environmental consequences of participatory governance, extend the frontiers of meta-analytical and field experimental methodology, and yield insights of value for policymakers and practitioners.