The research proposed here is addressed to answering questions about individual differences among newborn infants and the relationship of those differences to environmental stimulation. The proposal provides for the assessment of normal and high-risk newborns, for the assessment of environmental stimulation in hospital and home setting, and the repeated measurement of developmental progress. The design provides for normative assessment of 500 normal newborns and a comparative sample of high-risk newborns, and assessment of available environmental stimulation will be made for a sample of these infants while in the hospital and at home. Selected subsamples will be followed at 5 months of age and at 1 year of age. As a result of the research being proposed, we will be able to answer questions concerning the stability of individual differences, the relationship of individual differences and environmental stimulation, and the combinations between the two that result in differential developmental outcome. We expect to be able to propose strategies for the design of individual early stimulation intervention programs as the result of this research.