Cities as places of sustainability transformation are becom-ing increasingly important in sustainability and transition re-search. One of the key questions is how to proactively promote and spread urban sustainability niches. Real-world laboratories are an approach that uses experiments at the sciene-soci-ety interface to reflect sustainability challenges in a concrete (urban) context and to proactively foster complex transformation processes. This paper discusses real-world labs as spaces for experimentation and reflexive learning and introduces institutional logics and narratives as conceptual approaches to analyse these. This approach is illustrated using a case study from the real-world laboratory Wuppertal. Together with the civil society initiative “Utopiastadt”, an experiment was carried out to develop liveable urban space. Based on the results of the case study, key methodological features and the spe-cific understanding of experiments in real-world labs are dis-cussed. They are related to experimental approaches in planning science in order to discuss the different understandings and expectations with regard to the use of experiments as well as the potential contributions and complementarities between the two fields of research.