The phenomenon of political reintegration is getting ever more relevance under the conditions of the current development of social-political relations, however, theoretical approaches to this phenomenon are poorly developed. This work’s purpose is to analyse the theory of the reintegration phenomenon. As a result of the analysis of various definitions, the following definition is formulated: reintegration is the return of a social group, political party, group influence, state entity or territory to the corresponding object with which they were historically associated. The article also contains a review of theoretical and empiric literature on the problems of reintegration, identifying the characteristic features of the phenomenon and the features of its manifestation in different spheres of society. Current reintegration research is often related to the project approach and is aimed at solving problems of reintegration of territories and individuals. The conducted research indicates the opportunity for studying this phenomenon within the framework of political science.