The purpose of this study is to substantiate the approach to the selection of industries for program-target stimulation of regional economy diversification, focusing on developing new strong industries and increasing the economic complexity of the regional economy. The research methodology is based on the application of the concept of revealed comparative advantages and an assessment of the economic complexity of industries and regions of Russia (the Udmurt Republic, Republic of Mordovia, Kaliningrad Region, and Trans-Baikal Territory) using data on tax revenues by economic sectors. The novelty of this research lies in demonstrating the effectiveness of applying the revealed comparative advantage concept, an approach to assessing economic complexity based on the use of tax revenue data by economic sectors, and a strategy for modernizing intermediate opportunities when selecting industries for program-target stimulation of regional economy diversification. The practical significance of the results is determined by the possibilities of their use in the application of program-target mechanisms to solve problems of stimulating the development of individual sectors of the regional economy. Selecting priority areas for diversification based on economic complexity methods can contribute to the improvement of budget balancing, economic growth and sustainable development, and mitigation of interregional inequality.Β Doi: 10.28991/HIJ-2023-04-03-013 Full Text: PD