In spite of great national and international efforts and relative success in achieving technological and economic progress, the underlying situation in the Third World offers little cause for optimism. Some notable exceptions notwithstanding, in most countries poverty is increasing at an alarming rate, with its accompanying misery, poor health, and social unrest. Unequal distribution of material wealth, political instability, and the crumbling of traditional and cultural values are also increasingly prevalent. Critical assessment of the philosophy, goals, and methodology of development is an urgent requirement in many nations. Mental health endeavors in the Third World need similar reformulation of both immediate and long range objectives and methods, if ever-increasing mental health demands fostered by such rapid and sweeping changes are to be met. Four major models--the hospital-based model, the medical school-based model, the community-based model, and the voluntary organization model--have so far been the basis for mental health development in Third World nations and, to a certain extent, have produced the needed personnel and services. A fifth model--the primary health care model--seems to hold more promise for the future. By virtue of its integration with general health and other administrative social networks, it can more easily reach out to the community, providing both curative and preventive mental health. Whichever model or combination of models any one nation or region adopts, future mental health endeavors in the Third World should be an integral part of overall social policy and health planning. Taking children, family, and school as major foci, such efforts are indispensible and should constitute a positive force in shaping the continuing process of social evolution.