With this presentation I intend to put forward a new definition of urban porosity as a notion capable of describing the necessary rich quality coupling urban space and social and civic engagement. This is done through the analysis of the social space practiced by new urban social movements, and points to a new geography of social urban governance, which bears the potential of redirecting the policy and praxis of urban interventions. In the current context of the readjustment of large-scale economic and regulatory trends, it is not clear how the coupling of mixity and density alone is capable of articulating a sustainable and socially cohesive urban tissue without mobilizing its socio-political counterpart as a necessary form of reflexive urban governance. Within this problematic, porosity has been put forward as an operative notion capable of capturing and mobilizing capacities of urban space for affording a more adaptive socio-spatial continuum. Drawing on the seminal contributions by authors like Secchi and Dehaenne, I redefine porosity beyond physical or compositional dimensions. I pose porosity as an emergent relational property within a new frame of reference that draws from distributed cognition and environmental psychology. This is done in the context of the analysis of new urban social movements in Madrid, and how they change the geography and spatial scale of reference, questioning through actions at the small scale, a concept of Madrid of new residential peripheries at metropolitan and regional scale.