The aim of the PhD thesis is to assess support efficiency and effectiveness for electricity generation from renewable energy (RES-e) sources in Latvia and to work out suggestions how to improve it. Within the scope of this PhD thesis the term support for RES-e generation means economic stimulus or aggregate stimulus (instruments), which are determined in political planning documents and in the legislation, with the aim to attract investments in the field of RES-e generation that otherwise (without support) would not be invested. In the PhD thesis the author has analysed theoretical aspects of support for RES-e generation and concept of support efficiency and effectiveness; has studied the newest scientific thoughts about the positive impacts (effects) of the use of RES on economic, social and environmental welfare and energy independence; and about benefits and drawbacks of support for RES-e generation; has collected, aggregated and analysed the information about techno-economic indicators of development of RES-e generation; has conduced a research about the sector of RES-e generation in Latvia and analysed its development tendencies, potential, perspective and problems; has examined support regulations for RES-e generation in the EU and in Latvia and identified drawbacks of these regulations in Latvia; has reserached the actual situation about the support systems for RES-e generation in the EU, has made an interstate comparison of support tariffs for RES-e generation in the EU countries. Taking into account the results of the author`s assessment of historical growth of RES-e generation sector in Latvia and of the support regulations for RES-e generation in Latvia, the author has carried out analysis of support efficiency and effectiveness for RES-e generation in Latvia and has drawn relevant conclusions about the discovered problems, tendencies, and regularities and to find solutions and elaborate suggestions to improve support efficiency and effectiveness for RES-e generation in Latvia.