The paper reviews mental retardation research activities of the National Institute of Child Health and Human Development (NICHHD) and the National Institute of Neurological and Communicative Disorders and Stroke (NINCDS). Research activities are cited to illustrate the scope of NICHHD's efforts in a variety of biomedial areas. Activities are described for the following topics: malnutrition and development (effects of protein malnutrition on brain development in rats); Down Syndrome (use of mouse models to study genetic disorders); prematurity (identification of factors resulting in infant mortality, prematurity, and delayed or retarded growth and behavior development); fragile X syndrome (prenatal demonstration in cultured amniotic fluid cells); congenital hypothydroidism (effects of early treatment); phenylketonuria--PKU (assessment of the neuropsychological development of children with PKU); monitors to measure blood sugar; and psychophysiological processes (computer linked measurements of infant reactions). Activities sponsored by NINCDS center on metabolic disorders such as lipid storage diseases. (CL)