The article presents a comparative analysis of spatial development assessment methodologies used to diagnose inter-territorial differences, internal disparities, and asymmetries in socio-economic development. The aim is to identify the strengths and weaknesses of the main approaches with regard to the applied task of interregional comparison at the subnational level, and to assess their suitability for regular dynamic monitoring and for interpreting the detected deviations. The methodologies are compared against a set of criteria, including the scope of their applicability, the comprehensiveness of their domain coverage, the dynamism of their calculations and the interpretability of the causes of the imbalances they identify. In addition, account is taken of the specific features of the normalisation and weighting of the indicators, as these affect the reproducibility and comparability of the results. The review covers, as illustrative examples, the World Bank’s Adjusted Net Savings indicator, GDP-adjustment approaches (MEW/ISEW/GPI), multidomain quality-of-life models, and selected methods proposed by international and Russian authors aimed at diagnosing within-country spatial imbalances. The study results in a comparative matrix of the advantages and limitations of the reviewed methodologies, which makes it possible to identify their diagnostic potential, constraints on regional-level application, and sensitivity to methodological settings, and to highlight methodological elements most relevant for the subsequent development of an assessment toolkit for the territorial development of regions in the Russian Federation, taking into account regional data availability and the needs of policy-oriented analysis.