The article revises sociological theories, which focus on the phenomenon of social fragmentation. The movement of sociological interpretations and justifications of social fragmentation is shown starting from N. Luhmann’s theory to postmodern conceptions. The problem of the crisis of social fragmentation in modern Russian society is posed. Possible directions of theoretical search in sociology for new foundations of world-building, restoration of viability and integrity of the social relations and interactions are offered. In the analysis of the problem, the emphasis is made on fragmentation (and its overcoming) in the core of society – social communities. It is shown that the sociological theory addressing the phenomenon of social fragmentation, is generally characterized by an appeal to the community (group) level of social reality.