The circular economy is becoming a field of experimentation to trigger site-specific laboratories oriented towards connecting material flows and citizens' practices. Despite their wide use, a critical perspective of the transformative paths of these Urban Living Labs (ULLs) is still missing. This paper compares the paths followed by two such experiments, one in Amsterdam (The Netherlands) and the other in Turin (Italy). To this end, we build an analytical framework that targets three

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... unconventionality, autonomy, and systemic impact on policies. We conclude that ULLs can take very different transformation paths over time due to a wide range of enablers and barriers. In Amsterdam there has been an assimilation in the neighbourhood as well as a transformative effect on an urban scale; while the case of Turin has turned out to be potentially transformative but also at risk of marginalization.