This article stresses the heuristic power of the concept of community today, with particular attention to urban sociology. The authors distinguish between a cultural and a spatial meaning, focusing on the American debate through the concepts of community (cultural) and neighborhood (spatial). They look up these concepts in many Anglo-American encyclopedias; then, they consider the works of Barry Wellman and Robert Sampson. Wellman stresses the liberation of community from a place and the importance of mapping social ties and contacts. Sampson stresses the liberation of neighborhood from the logic of primary group relationships, so neighbor- hoods are seen as more ecological than affective units. So, the American debate seems to confirm that two notions of community are required: community is connected to individuals, networks and strong ties, neighborhood is connected to socio-spatial organization and "collective efficacy".
Keywords: Community, neighborhood, socio-spatial, socio-cultural, community liberated, collective efficacy