Infrastructures and utility services are fundamental to economic and human development. Therefore, investment in these areas is critical to economic growth, quality of life, poverty reduction, access to education and health care and achieving many of the objectives of a robust economy. Yet, whereas the public sector provides the vast majority of financing for infrastructure services, investments have not matched demand, public funds or borrowings are insufficient and governments are seeking methods to improve the efficient procurement of infrastructure services.Private sector participation in public projects is increasingly becoming a reliable source of investment and, as far as public policies are concerned, an unavoidable feature of our contemporary society even in “core public policies” (for example, greater responsibility for financial planning and welfare provision is being increasingly shifted by the states to the private sector and individuals). In the area of infrastructures and utility services, Public-Private Partnerships (PPP), despite some of their challenging features, are one of the tools in a policy maker’s arsenal which help to increase investment in infrastructure services and improve its efficiency. One of the main advantages of PPP is that, unlike privatization, the government retains strategic control over the project and the ownership of its assets. PPP offers multiple options or structures.As shown in this study, Build, Operate and Transfer (BOT) Projects are one of the numerous options offered by PPP. In a BOT project, a private entity is given the right to design, finance, build and operate for a defined period (“concession period”) a facility that would normally be built by the government. The operation of the project generates revenues and the private entity uses these revenues to service debt and provide the investors with a return. At the end of the defined period, the private entity turns over the facility to the government. In practice, a number of parties – each with sometimes different interests, levels of sophistication and available resources – will be involved in a BOT project: the grantor/host government, the sponsors (generally throughout the project company), the lenders and the contractors (construction contractor, operator, offtake purchaser, input supplier) and the BOT approach can be used for different and various projects (power generation, water treatment, airports, roads, tunnels, bridges…) and, hence, has many variants such as BOO (Build, Own and Operate), BOOT (Build, Own, Operate and Transfer), BTO (Build, Transfer and Operate) etc.The ambition and objective of this study is therefore to give a full understanding of the BOT concept and to shed light on its originality and its unity. The BOT concept is therefore considered as an economic cooperation device, demonstration made in this study principally under the light of law and economics approach. In effect, structuring a BOT project requires the use of (free) market tools (especially economic and financial tools), which render the law and economic approach perfectly suitable to analyze the BOT concept and reveal its rationality and coherence. Hence, the use of the (strategic) game theory to underline the mutual gains resulting from the cooperation between partners involved in a BOT project; the use of the incomplete contract theory to explain the special care needed to design the BOT contract and its possible adjustments; the use of the theory of the firm and financial contracting to explain the functions of coordination and integration of the project company; or also the use of the public choice theory to analyze the notion of general interest which has led to the conclusion that BOT projects are a combination of public and private interests in order to achieve optimality and mutual gains.