Presented are 18 papers on problems in the psychology of mentally retarded children. Seven of the papers are in English, two in French, and nine in Russian. The English papers are concerned with the following topics: peculiarities of psychic functions in oligophrenic (retarded) children with pronounced underdevelopment of frontal lobes of cerebral cortex, the principle of endogenous and exogenous classification of mentally retarded children, a review of studies on concrete thinking of oligophrenic children, guessing behavior of normal and retarded children under noncontingent reinforcement conditions, the identification of learning strength of mentally handicapped children, problems such as lack of goal orientation in the activity of mentally retarded children, and the rehabilitation of higher cortical functions of children with cerebral palsy. French papers discuss motor development of mentally retarded children, and social and job related characteristics of mentally retarded adolescents. (DB)