After a survey about the historical development, the paper deals with the different institutions that are working for the realization of the old demand for a co-operation of scientists and technicians of different nations today. The abundance of the international organizations can be grouped in non- public and public enterprises. Some among these have only to perform tasks of organization and administration and other concrete functions in scientific research or technical research and its industrial applications. Finally the or- ganizations of world-wide membership differ from those whose members are restricted to certain geographical regions. In view of the diversity of the international organizations and their rela- tionships it is not easy to presume which road future development in this prosperous field of international co-operation will take. At any rate it is of greatest importance for the scientists to watch over the development and to determine its direction, in order to guarantee the difficult balance between spiritual freedom and material dependence. Resume Se basant sur un apen; u de l'evolution historique de la seienee et de la recherche, eet expose traite des differentes institutions, dont la fonetion est de realiser aujourd'hui le desir d'une eooperation entre les hommes de la seienee et les teehniciens des differentes nations.