In their quest to create vital cities, West European city governments stimulate citizens to self-organize in citizens' initiatives. This trend it accompanied by conflicting scientific and governmental discourses: on the one hand, citizens' initiatives are praised for giving ‘power to the people’, on the other hand, citizens' initiatives are understood as mere ‘tools’ to roll-out government policies. By adopting a critical-constructive perspective, this study sets out to better understand the paradoxical attitudes of local governments toward the potential of CIs for stimulating urban vitality. We do so by uncovering patterns that explain the opening and closing of spaces for citizens to develop their initiatives. To this end, we conducted an in-depth case study into the relation between the local government and citizens initiatives in the energy transition in Rotterdam (the Netherlands). Our findings reveal that a configuration of different explanatory mechanisms leads to the ‘domestication’ of initiatives, which jeopardizes their unique transformative potential that can contribute to the vitality of cities.