This thesis investigates, for the first time, contemporary regulation practices for the nascent private health care sector in Mongolia for the achievement of Universal Health Coverage (UHC). The number of private health care providers has been increasing dramatically in Mongolia during the last two decades. Identifying conducive ways of harnessing and regulating private health care providers is a pressing policy issue for the Mongolian mixed health system in moving towards UHC. However, this issue is yet to be extensively examined. No evidence currently exists on the role of private providers and the appropriateness of current regulatory policy for the achievement of UHC. The "what, how, and why' of the constraining and enabling factors of effective regulation remain largely unknown. This lack of evidence on the contribution of private providers affects not only Mongolia, but developing countries generally. Hence, this comprehensive and rigorous case study of regulation of the private health care sector in Mongolia makes a significant contribution to the advancement of regulatory policy and practices in that country, and informs similar developing countries, in particular, Post-Soviet states. This thesis uses a case-study approach employing both qualitative and quantitative methods. First, in order to define the current role of private providers in the provision of accessible, affordable, and equitable health services, nationally representative hospital admission records for 2013 (n=664,952), have been analysed. This quantitative analysis was supplemented with a qualitative analysis of in-depth interviews and document reviews to clarify findings. Second, to identify the gaps in regulatory policy design and implementation, stepped qualitative analysis by Sheikh et al. (2015) has been employed. Document review and analysis were complemented by participant observation and semi-structured in-depth interviews with 45 purposively-selected key informants. Third, to understand how and why regulation of private health care fails or succeeds in Mongolia, regulatory policy analysis has been conducted. The main sources of data used are the analytical synthesis of research findings, in-depth interviews, document reviews, and long-term participant observation of evolution of the system in Mongolia. This thesis has found that until this point, the contribution of the private sector to improving the system performance has been limited. Private-for-profit hospitals are concentrated in urban areas (60% of private hospital admissions were located in Ulaanbaatar, while 95% of private admissions outside Ulaanbaatar were in provincial capitals), deepening the existing rural/urban mal-distribution already established by public providers. Subsequent duplication of public and private services, both iii in terms of their geographical location and the range of services delivered has led to unnecessary admissions and unnecessary health care costs, having negative financial implications for both patients and overall health expenditure. This ...