After the World War II, developed countries have been engaged in a race on economy, armory and superiority including testing new weapons without considering environment. On the other hand, undeveloped countries tried to catch up with developed countries as soon as possible in terms of economy and technology and they also kept ignoring the environment. During occurrence of environmental pollution, important international meetings were held on the subject. At the end, it was understood that the only solution was sustainable development after long discussion. In that model, meeting the needs of the present populations without compromising the ability of the future generations to fulfill their own needs is aimed. Of course, this is not easy but, it was unanimously accepted at the various meetings that humanity must succeed it. Thus, it is necessary to change our understanding on planning approach and consider sustainability in investment projects as a basic concept. In this article, conclusions of the meetings were evaluated and some proposals were made to contribute to the solution of the problem.