The article proposes an original methodology for assessing the stability of the spatial development of the regions of Siberia and the Far East of Russia through the prism of the component of the triad of sustainable development. The results of the calculation of the Index of Sustainability of Spatial Development of Regions (SPR) are presented. On the basis of the Index all regions were divided into 3 groups: Priority – “sustainable”; Functioning – “stable”; Problem – “unstable”. The assumption is formulated that, due to the differentiation of natural landscapes - from comfortable to absolutely unfavorable, multiplied by the variable severity of the climate - extensive territorial development is not required for the spatial development of a number of subjects of the Siberian and Far Eastern federal districts. Renovation of the network of outposts and infrastructure, a selective policy for the development of settlements, the shift method (with a minimally sufficient set of social functions) will bring a much greater effect. The importance of the transition from the redistribution of resources to the redistribution of opportunities and equalization of the investment attractiveness of the regions of Siberia and the Far East (the creation of conditions attractive for the growth of capitalization of territories and, accordingly, improving livelihoods and sustainability) is emphasized. From a practical point of view, the results of the study can be used in variant scenario planning of the spatial development of the country's regions.