Participation of citizens and stakeholders in public environmental decision-making has grown significantly over recent decades, but its effectiveness for environmental governance remains highly contested. In order to explore the impacts of participation on quality of environmental decisions and their implementation, we carried out a case-survey meta-analysis of 200 cases of public environmental decision-making in western democracies. Utilising a theoretically-informed analytical scheme, we coded for each case 315 unique variables characterising decision-making processes, outcomes, outputs, impacts, and context factors. In addition we coded 28 key hypotheses derived from the literature, to explore important causal mechanisms at play. Based on methods of statistical inference, we find that process-related variables correlate significantly with environmental outputs and outcomes, but that these are highly dependent on various contextual conditions. These findings are highly relevant to theory and practice as to the conditions under which different forms of participation ‘work’ in environmental governance.
