Social and Solidarity Economy (SSE) initiatives and urban commons experiences have grown exponentially in the last 15 years in Catalonia, which has further led to an increase of collaborative experiences with public authorities. The relationship between the State, community-led, and SSE initiatives is often complex and characterised by an heterogeneity of collaborative experiences. Further research is needed on how the collaboration is formalised and shaped at the policy level, its governance forms, its challenges and conditions that enable a sustainable collaboration. In this paper, we characterise the collaboration between the public administration and SSE organisations by investigating the public policy of the Network of Cooperative Athenaeums. Our findings show that the policy promotes a multi-level public-community-cooperative governance model allowing collaboration between first, second- and third-level organisations. This space advances the relationship towards commons-led coproduction. It aids the growth of the SSE and their networks, the spreading of SSE values, and the development of legal frameworks, accommodating the challenges and tensions of the collaboration. However, further research should consider actors outside the SSE (e.g. commons, social movements).