Abstract: The subject of this research is the development of the concept and methodological approaches towards formulation of the theory of reputation economy applicable to the regional economic systems. This suggests not only formulation and substantiation of theoretical foundations, but also securing theory with practical recommendations based not so much on the methods of qualitative analysis, as on the methods of quantitative modeling of the studied processes using a wide variety of mathematical models. The object of this research is the Republic of Tatarstan. Special attention is given to the formalized assessments of the impact of reputation capital of the theory upon the parameters of its investment activity. The developed methodological approaches form the foundation for its further improvement and may enhance a dialogue on the indicated problematic – assessment of the impact of the reputation of theory upon investment processes. The scientific novelty of this research consists in the formulated conceptual approach of quantitative assessment of reputation capital of the region, as well as towards the development of the theory of reputation economy applicable to the regional economic systems. The research results determine the quarterly values of integral indexes of reputation capital of the Republic of Tatarstan over the period from 2013 to 2017, which formed the basis for structuring the econometric models of its influence upon the parameters of investment activity of the territory.