The issue of the protection of minorities has been one of the main concerns of International Law and the international system, especially in the twentieth century. For pragmatic, as well as humanitarian reasons, the International Law has been a protective instrument, since minority question has never contained itself entirely within the national boundaries. With the establishment of two international governmental organizations in this century, the system for the protection of minorities has entered into a new era, and its organizational framework gained a considerable significance. Together with the fundamental human rights, the concept of “collective rights” have also become a subject for the public, governmental and intellectual discussions, especially during the second half of the twentieth century. This study aims to examine the evolution of the system for the protection of minorities in International Law, from its beginning in the thirteenth century until 1990. However, it basically focuses on the guarantee and protection systems established by the League of Nations and the United Nations on the protection of minorities. It also examines the written documents and important initiatives of some regional organizations, such as Organization on Security and Cooperation in Europe (OSCE, originally called Conference on Security and Cooperation in Europe). Moreover, the conceptual and definition problems of the issue are given a considerable place in the thesis. It argues that, in spite of the positive developments in International Law, the system of the protection of minorities should be elaborated, by considering distinct characteristics and aspirations of the minorities as a collective entity.