The article gives a detailed analysis of modern concepts of social structure by A. Giddens, P. Bourdieu and J. Urry. The author identifies and conceptualizes a particular area of middle dialectical ontological categories, representing the mesostructure with a gradual transition from A. Giddens’ and P. Bourdieu’s integrative concepts to J. Urry’s concept of mobile fluid structures. Such middle dialectical ontological categories as the duality of structure (A. Giddens) and the process of double structuring of social reality (P. Bourdieu), as well as their derivatives — the categories of social practices (A. Giddens) and habitus (P. Bourdieu) are examined in detail. The transition structuring iterative principle of J. Urry’s “mobile sociology” allows understanding how different the integrative concepts based on the principle of recursiveness are from the concept of mobile fluid structures. Particular attention is paid to the nature and transformation of the concept of inequality within these sociological concepts.

Keywords: social structure, middle dialectical ontological categories, integrative concepts, flows, A. Giddens, P. Bourdieu, J. Urry