The article studies the investment foundations of the economic specializations of the constituent entities of the Russian Federation. In the conditions of the modern economic environment, the study of investment fundamentals for the economic specializations of the constituent entities of the Russian Federation is of particular importance. This is due to a number of factors that determine the need for a more in-depth and comprehensive analysis of the investment component of regional economic development: the study of investment fundamentals allows us to identify potential areas of economic specialization, which in turn contributes to a more efficient allocation of resources and the development of development strategies; studying investment fundamentals allows us to identify problematic issues that hinder investment in certain industries or regions; the third aspect is related to the need to determine the potential of regions for the development of specific types of activities based on an analysis of investment fundamentals. This is important both for the formation of strategies for the development of the regional economy, and for making informed decisions on areas of attracting investment. The subjects of the Volga Federal District are considered as the object of research, special attention is paid to the Orenburg region. The subject of the study is economic, organizational, financial and production relations that arise during the formation of the investment foundations of the economic specializations of the constituent entities of the Russian Federation. The purpose of the study is to study the economic specialization of the region based on an assessment of interre- gional differentiation. The article proposes methodological support for studying the investment foundations of eco- nomic specializations of the constituent entities of the Russian Federation based on methods of comparative and retrospective analysis, as well as regression modeling. It is highlighted that investments in fixed capital are a signifi- cant factor in the development of economic specialization of the region. The results of the study can be used by scientists for further research in the direction of developing the economic specialization of the region based on assessing the size and level of investment in fixed capital.