This paper explores the institutional mainstreaming of nature-based solutions (NBS) to advance a process-based understanding about how to strategically develop the governance capacities needed for systemic, localised and inclusive NBS. To this end, it reports how policy officers in ten European cities have started to mainstream NBS by interacting with and changing incumbent governance arrangements when experimenting with novel governance processes and mechanisms to plan, deliver and steward NBS. Based on these activities of the policy officers, the analysis identifies three strategies, associated stepping stones and changes in governance conditions, to mainstream NBS in governance capacities: institutionalising (a) a systems’ approach to link NBS to policies, regulations, and departments across goals and sectors, (b) inclusive collaborations for localised and inclusive interventions, and (c) reflexivity and learning about how NBS interact with the (institutional, ecological, social, etc.) contexts and create impacts. The strategies illustrate institutional entrepreneurship in interacting with incumbent governance contexts, and how starting from NBS as a type of systemic innovation can promote broader shifts in urban governance arrangements.

Adaptive governance is an emerging theory in natural resource management. This paper addresses a gap in the literature by exploring the potential of adaptive governance for delivering resilience and sustainability in the urban context. We explore emerging challenges to transitioning to urban resilience and sustainability: bringing together multiple scales and institutions; facilitating a social–ecological-systems approach; and embedding social and environmental equity into visions of urban sustainability and resilience. Current approaches to adaptive governance could be helpful for addressing these first two challenges but not in addressing the third. Therefore, this paper proposes strengthening the institutional foundations of adaptive governance by engaging with institutional theory. We explore this through empirical research in the Rome Metropolitan Area, Italy. We argue that explicitly engaging with these themes could lead to a more substantive urban transition strategy and contribute to adaptive governance theory.