Ripensare la Sociologia urbana. Parte prima: specificità disciplinare e variabili in campo - Re-thinking Urban Sociology. Part one: disciplinary specificity and field variables, In his paper Paolo Guidicini proposes a profound reflection on some basisconcepts for Urban Sociology. The goal is outline the essential elements to rethinking the urban sociological research, from re-conceptualisation of urban actor to a re-interpretation of human/urban link, across the analysis of two classical binomial as homogeneity/heterogeneity and identity/identification. Key words: urban sociology, cognitive surplus, city of the third world.