Studies show that municipalities often develop a type of urban greenspace that is rather uniform in its shape and use. Citizens’ initiatives develop different types of greenspace. This article uses concepts from transition studies and identifies what happens during a citizens’ initiative in urban greenspace in the Netherlands in terms of transition of municipal management and development and how these initiatives can lead to a change of practices of the municipality. A single, qualitative study of Diepenheim Inside-Out-Forest in the Netherlands as a critical case is presented, based on 8 semi-open interviews. The study gives insight in how the municipality has changed in relation to this one case, and how such transition of ‘regime’ takes place. The study explains how the different benefits that arise in a greenspace development and management initiative relate to the ‘critical knowledge’ and ‘situated knowledge’ of the actors involved and that the quality of urban greenspace is very much the result of that knowledge. ‘Fit and conform’ and ‘stretch and transform’ are usable strategies for the empowerment of such initiatives through sharing of resources, and policy advocacy by ‘critical niche’ innovators. ‘Regime’ is not uniquely a feature of the local state but also of market parties and citizens themselves with their own values and routines. A change among all parties seems needed if greenspace is to be developed, managed and used differently.