"Current political trends and scholarly research increasingly promote collaborative and participatory governance in multi-level systems as a pathway to more sustainable and effective environmental policy. Such decision making, so the hopes, could yield better results and a swifter, more broadly accepted implementation of measures. Nonetheless, the research gap between desire and reality is large. Countless case studies on (participatory) environmental governance have been published, but never systematically reviewed. A meta-analysis of 47 case studies from North America and Western Europe is designed to close this gap and shed light on the hopes placed on participation."