Social work is a complex system that interacts with other systems in society, and inevitably undergoes changes both from the influence of internal and external factors. Ukrainian society is under the influence of transitivity; therefore, an urgent need arises for the formation of an effective system of social work in modern realities. It is necessary to point out the significant number of studies devoted to the characteristics of a transitional society, its features, in the discourse of modernization and transformation processes, as well as in the socio-philosophical aspect. The author presents the essence of the social sphere and social policy as a system of vital functions of society and its components, where it is expedient to include social work. Social work is naturally associated with changes in social relations and the life of man and society, is a key tool in the implementation of the most important areas of state social policy. It is social work that ensures adherence to the principle of social justice by providing various types of social support to vulnerable groups of the population and reducing the exclusion and is a priority integrated mechanism for the practical implementation of the main tasks of social policy implementation. Analysis of the definition of «transitivity» and «transition» allowed highlighting the characteristics of the interpretations: as a transition, the gap between the states of social development; as uncertainty and multidimensional variants of socio-economic changes; as the newest form of socio-economic relations. Both negative and positive features of a transitiional society are singled out. It is proved that the effectiveness of the system of social work in these conditions will significantly increase if you apply the principle of multimodality, which allows you to combine different means of achieving the goal. Introduction of this multimodal social work system is possible taking into account certain conditions and observance of a clear implementation algorithm, where human capital plays a major role.