A statement of goals and the rationale for organization precede a historical discussion of mental deficiency and society. The problem of labels like IQ and brain injured and the consequences of the diagnostic process are illustrated by case histories; case studies are also used to examine the criteria used to decide who is retarded and to discuss the concept of cultural deprivation. Educational intervention and the effects of special classes, a 30-year study by Harold Skeels on the effects on institutionalization, and the climate of institutions and the problem of change are considered. M. Michael Klaber presents a preliminary research report on institutions and the retarded, and Frances Kaplan reports the development of a study on siblings of the retarded. Also discussed are the following: biological science and social attitudes, the origin and development of eugenics, and the use and misuse of Mendelism, sociopolitical factors in science, intelligence testing and social indictments, eugenics, and racism. Phenylketonuria, mongolism, other chromosonal anomalies, brain damage, and infantile autism are etiological factors described. (RP)