One of the far-reaching changes in the past century is the rapid growth of international organizations. International organizations are instruments for institutionalized co-operation among states; however, they also generate growing risks to other actors in the international system. The increased activity of international organizations may lead, naturally, to an infringement of the rights of others and the infliction of damage upon them. In such cases the question arises of which legal principles apply to the relations between the wrongdoer organization and the victims of its activity. This is the realm of responsibility of international organizations. The sphere of responsibility is interesting in that reality has preceded the development of the law. The rapid expansion in the activities of international organizations has not been accompanied by a parallel development in legal theory concerning their international responsibility. Contemporary international law is not, as yet, well developed in this field and many significant questions remain without satisfactory answers. This study aims to fill the gap in the present legal literature by clarifying the existing rules of responsibility of international organizations and through discussions of new proposals for areas uncovered by contemporary law.