A sample of 77 institutionalized children diagnosed as mentally retarded without other neurological signs or symptoms (familial-cultural retardates) was examined anthropometrically as well as for I.Q., birth weight, parental age, birth order, age at admission, and length of time spent in the institution. Compared to a control population of Philadelphia children, our sample was smaller in every measurement but one. Birth weight, parental age, and birth order were not remarkable. Correlations of several of these variables showed that children of low birth weight were smaller and less intelligent; I.Q. was not related to size; larger and brighter children were admitted at a later age; length of institutionalization was not related to size or I.Q.; and the older children were not proportionately less intelligent or smaller.