This dissertation is on the Practice of the Principle of Permanent Sovereignty over Natural Resources (PSNR) in Investment Industry in Tanzania, mining and natural gas being the case study. The principle of PSNR vests sovereign right of ownership of natural resources with all state. Among others, it includes the right to manage, control and benefit from the natural resources found within boundaries of the exercising state. Alongside of these rights, there are duties which states are bound of, which among others include the dutyof a State to Exercise the principle of PSNR in the Interest of National Development and the Well-being of the People. In spite of all rights and duties envisaged in the principle, and despite of massive investment in Tanzania, still it is evident that there are disputes arising out of investment in natural resources as well as challenges which face economic development. Tanzania is in dilemma concerning the destiny of her natural resources and the welfare of her citizens irrespective of the Principle of PSNR. There are issues of foreign companies dominance in the industry of investment in mining and natural gas, there are issues of confidentiality of investment contracts, there is a challenging factor of who is the beneficiary of natural resources, specifically gas and minerals between the state as an institution, indigenous people (ordinary citizens where natural resources are located) and few political figures. This dissertation analyses the practice of the principle of PSNR in mining and natural gas in Tanzania. The dissertation makes a thorough analysis of the practice of the principle in mining and natural gas sectors separately and it makes a comparison of the two. And more specifically evaluates the concept enshrined in the principle of PSNR, examines the legal regimes regulating investment in mining and natural gas in relation to the principle of PSNR, examines the institutional framework concerning investment in mining and natural gas in relation to the principle of PSNR, assesses the challenges facing investment in mining and natural gas in relation to the principle of PSNR and makes critical comparative studies on other jurisdictions namely Namibia, Zimbabwe, Kenya, Algeria, Democratic Republic of Congo, Libya, Venezuela, Bolvia and Ecuador with regard to the general practice of the principle of PSNR. Whereas from this scope, this dissertation suggests possible improvements and way forward in achieving the xv objectives of the principle of PSNR specifically out of investments in mining and natural gas industry in Tanzania. The researcher visited Geita and Mtwara Regions so as to ascertain the real situation on the ground. Apart from that, there are data collected from Tanzania Investment Centre, Tanzania Revenue Authority, Tanzania Minerals Audit Agency, State Mineral Corporation, Ministry of Energy and Minerals, Tanzania Investment Bank as well as from other ordinary citizens and lawyers. This dissertation reveals that, the ownership, management and control of natural resources is vested to the state as a trustee of its people, however there is no any legal provisions which expressly stresses that the state shall own natural resources on behalf of its nationals. It is established that, the existence of the State depends on four major ingredients which makes it one institution and they are indivisible. And this institution is what is vested with the sovereign right over natural resources. But this practice on the ground faces a list of challenges. Among others, the majority part of the people does not agree that they own natural resources, rather few political figures and elites within this system. Again, competition among developing countries for foreign direct investments, Bilateral Investment Agreements, lack of transparency inlegal and institution frameworks functions, poor technologies and lack of committed leaders are among noted challenges facing the practice of the principle of PSNR in investment industry in Tanzania. Basing on those challenges, the dissertation goes further to suggest possible ways which may be adopted for the better practice of the principle of PSNR from which at the end the intended aims of economic development and self-determination of the people can be achieved.