This report covers two years of research into the factors that determine the success or failure of green initiatives by businesses and citizens and their contribution to biodiversity. The researchers investigated fourteen initiatives by means of interviews and a document analysis, and selected five of these initiatives for more exhaustive case studies. First, they interviewed the initiators. For the case studies those interviews were supplemented with a further ten interviews with local government officers, elected municipal councillors and members of the municipal executive. Websites and policy documents were also analysed and almost all the initiatives were visited. The study made use of the policy arrangement approach by Arts and Van Tatenhove and took note of the theory of change under this approach. The research questions that were answered concerned how the initiatives came about, the initiators’ ambitions, the success and failure factors, local government involvement, and options for improving the response by local government to these initiatives, and to green initiatives in general, from the perspective of the local government respondents. The research showed, among other things, that the initiatives led to a greater variety of green spaces. A number of these initiatives enhance biodiversity in terms of species and habitats, including rare species. Besides answers to the research questions, the report contains recommendations on the Green Deal on New Urban Nature and to local government, as well as suggestions for further research.