Abstract: Many neighbourhoods are currently serving as laboratories where new methods are being explored for collaboratively redesigning cities and tackling the social, environmental, and cultural issues affecting them. These redesign processes are often supported by local communities who increasingly develop bottom-up initiatives to innovate and preserve the neighbourhood’s “common goods.” This is certainly the case of Nolo, an area in the city of Milan (Italy) that has recently undergone an urban regeneration process thanks to the presence of a proactive community of actors living and working in the neighbourhood. Despite effective social innovation practices enacted by part of the local community, several “voices” in Nolo—mainly belonging to marginalized communities—are still excluded from the current process of urban regeneration. This lack of attention is rather problematic for the whole community, as it is leading to increasing rather than mitigating social polarization. To address this issue, we approached Nolo and its community through a participatory design experimentation, generating a series of collaborative platforms to enable those marginalized voices—humans as well as non-humans—to be heard, to enter into agonistic conversations with one another, and to question what they (should) all care about. What this (still ongoing) experimentation is currently showing is that to co-design collaborative platforms to counter polarization needs to be carefully balanced, negotiating between all the actors involved and acknowledging their thick entanglements to finally unravel how they radically inter-depend on one another. This kind of “ontologizing” practice is currently proving to be pivotal to counter “antagonisms” (and, therefore, mitigate social polarizations), and re-framing them in “agonistic” terms. This article reports how we operated this “ontologizing” practice in a particularly debated area of the neighbourhood by embracing the perspective of marginalized actors, encouraging them to collaborative and transformative actions for their own situated context.