As widely attested in the literature, the evaluation of co-production is complex and unsuited to the use of conventional quality, monitoring and evaluation indicators. This reflects the uncertainties, co-contributory factors and time lags involved, particularly when seeking to assess institutional and wider societal effects of multistakeholder participatory processes and deliberative fora. The most widely assessed effects include the immediate outputs and outcomes of a project or activity (socalled first order effects) while wider societal or third order effects continue to be the most difficult to capture and, consequently, are the least well studied. Because of this difficulty, the intermediate, second order effects of organisational transformation and policy implementation constitute a growing challenge for evaluation. This is our focus here. After 10 years of transdisciplinary co-productive research practice, Mistra Urban Futures, as an interstitial research space bridging academia and practice working through city-based institutional partnerships called platforms, has reached a phase where some of these effects are becoming distinguishable. Accordingly, we discuss the prerequisites for co-production practitioners, including policy makers, to engage their respective organisations in transitional and incremental experimentation in order to achieve relevant institutional changes. This requires enabling infrastructures that support training, facilitation and the creation of ‘safe’ spaces to promote trust and legitimacy. These are needed to underpin the longlasting personal and organisational commitments which are crucial to achieve transformative organisational effects.