The article analyses the issue of Sharing and Collaborative Cities from a primarily methodological perspective. Starting from statistical data that confirm the constant growth of the urban population, and taking into account the major issues that affect urban policies (environment, inequalities, poverty), the author focuses on the different methodological approaches in the study of collaborative cities. Subsequently, an Italian case study is presented, which involves shared administration and the main implementation tools involved (Regulation of the management and regeneration of urban commons, including collaboration agreements).