In Santa Coloma de Gramenet (Catalonia, Spain) there is a network of four public libraries. They belong to the City, with technical assistance, strategic orientation and financial support from the provincial government, Diputacio de Barcelona. These four libraries have been built in different historical periods and located in ´ neighbourhoods with very unequal social backgrounds. They have been working on adapting their services to their neighbourhoods and as a network they have been moving on along the differences. Even so, the current information society challenges require a city library project in order to guarantee social cohesion and equal opportunities. This article tries to explain the strategy to achieve those goals, based on knowledge management and networking, transversal workshops and a shared communication circuit that so far has allowed this urban library network to extend and to renew services as well as to empower vulnerable sectors in accordance with the United Nations 2030 Agenda.