In Brazil, social housing complexes produced through participatory design and participatory construction processes inventively activate existing urban commoning traditions. In Mexico, advanced potentialities of emancipatory commoning are created in self-managed autonomous neighbourhoods produced by politically engaged social movements. Both the Brazilian homeless movement projects (crucially aided by groups of militant experts) and the Mexican autonomous neighbourhoods draw from the rich tradition of the pioneer Uruguayan cooperatives that developed a model of social production of housing based on mutual help practices and the institution of collective ownership. This text focuses on the potentialities for participatory design that were opened and performed in the above cases. What kind of shared values made possible those collective experiences? In what ways was the idea of the common reformulated? Is there a prefigurative element in such spatial practices that gestures towards an emancipatory urban future?