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. 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. The analysis identifies three strategies to mainstream NBS in governance capacities: institutionalising (a) a systems' approach, (b) inclusive collaborations, and (c) reflexivity and learning. These strategies illustrate institutional entrepreneurship and how starting from NBS as a type of systemic innovation can promote broader shifts in urban governance arrangements.

Katharina Hölscher, Niki Frantzeskaki, Marcus John Collier, Stuart Connop, Esmee D. Kooijman, Marleen Lodder, Siobhan McQuaid, Paula Vandergert, Dimitra Xidous, Lejla Bešlagić, Gillian Dick, Adina Dumitru, Agnieszka Dziubała, Isobel Fletcher, Cristian Garcia-Espina Adank, María González Vázquez, Natalia Madajczyk, Eleni Malekkidou, Maria Mavroudi, Eleftherios Loizou, Agnieszka Osipiuk, Belma Pašić, Antonio Prieto González, Mien Quartier, Selina Schepers, Nermina Suljević, Ivaylo Trendafilov, Katrien Van De Sijpe, Velichka Velikova, Peter Vos