The objective of this paper is to describe a research program at MIT (USA) for the application of modern investment criteria and mathematical modeling techniques for water resources planning in Argentina. The project lasted for two years and had three principal objectives: (1) to adapt modern water resources planning techniques to Argentina; (2) to train Argentina professionals in the use of these techniques; and (3) to apply the techniques to a basin in Argentina for the purpose of developing alternative management and development plans for the river responsive to alternative economic and social objectives. In considering the use of systems techniques in developing countries, the organization of programs to apply them; the nature of the available techniques; and applications of them are all of interest and importance. Accordingly, in this paper key organizational features of the MIT-Argentina program are described; the nature of modern water resources planning methods is outlined; and the system of models developed for the case study is described. Finally, a few tentative conclusions about the study are presented.