This survey is directed toward the implications for the mental health of the people of the world who are effected by the introduction of technical change. It deals with the ways in which changing agricultural or industrial practices, new public health procedures, new methods of child and maternal health care, and fundamental education, can be introduced so that the culture will be disrupted as little as possible, and so that whatever disruption does occur can either by compensated for, or channelled into constructive developments for the future. It stresses a broad epidemiological approach in which the individual is seen within the society.