The presumed influence of early home environment on mental retardation in children provides the theoretical rationale for many compensatory and special education efforts. Supportive research in this area has been hampered by the unavailability until recently of sensitive measures of the environment resulting in heavy reliance on status (i.e., social class) characteristics as the primary basis for judging the quality of the child's developmental environment. The investigators have developed an instrument (the HOME Inventory) which assesses key components of parent-child interaction and the availability of growth-fostering materials and experiences. Early publications by the investigators dealing with the developmental correlates of HOME patterns led to requests from many researchers to use the instrument. The present project will create an interdisciplinary consortium involving six research centers, each of which will supply a cohort of already existing data totaling almost 1900 children and families. Pooling of these data from a range of social classes, geographic regions, and ethnic groups will allow sophisticated data analyses to be carried which would not be feasible in any one center. Major analyses to be conducted include correlations between HOME scores and SES scores and child cognitive measures for different subgroups as well as the total group; regression and pathe analyses involving environmental and developmental variables; and factor analyses of home environment data at different time points. Comparisons of environment/development relations by sex, ethnicity, degree of biologic risk, family structure will be made as will a comparison between a matched group of children with IQ's below 70 and those with IQ's in the normal range. Findings from the consortium study should facilitate the formulation of more objective generalizations about the complex relationship between home environment and mental retardation, and the establishment of more effective educational programs.