This paper addresses itself to three aspects of world food and fiber needs and the protection of the ecosystem. The first is to distinguish between food and fiber needs of the world on the one hand, and the production of food and fiber in developing countries as part of a long-term process of economic development on the other. The second area of attention is the role of science and technology in the process of agricultural modernization and development. Finally, we will look at a class of problems dealing with socially costly externalities associated with agricultural development and the use of new technologies.