The Article observes the theoretical grounds of social work, which are presented by the Authors as the interdisciplinary sphere of science, which is closely connected with different socio-humanitarian disciplines. The subject field of modern social work and its conceptual framework are proved. The role of social reflection in forming theoretical basis of social work is analyzed. Basing on the judgment and critical analyses of the range of existed trends of social work theory the Authors offer to observe the holistic structure “ human being - environment - their interaction regulators” as the uniting beginning of comprehensive theoretical basis of social work.