The Early Growth and Development Study (EGDS) is a prospective adoption design consisting of 360 linked sets of birth parents, adoptive parents, and adopted children followed from 3 months postpartum through child age 7 years and an additional 200 linked sets for whom recruitment is underway. The EGDS brings together the study of genotype–environment correlation and Genotype × Environment (G×E) interaction to inform intervention development by examining mechanisms whereby family processes mediate or moderate the expression of genetic influences. Participants in the EGDS are recruited through domestic adoption agencies located throughout the United States of America. The assessments occur at 6-month intervals until child age 4½ years and at ages 6 and 7, when the children are in their 1st and 2nd years of formal schooling (kindergarten and first grade). The data collection includes measures of child characteristics, birth and adoptive parent characteristics, adoptive parenting, prenatal exposure to drugs and maternal stress, birth parent and adopted child salivary cortisol reactivity, and DNA from all participants. The preliminary analyses suggest evidence for G×E interaction beginning in infancy. An intervention perspective on future developments in the field of behavioral genetics is described.