We propose a theory of development in which experience is directed by genotypes. Genotypic differences are proposed to affect phenotypic differences, both directly and through experience, via 3 kinds of genotype → environment effects: a passive kind, through environments provided by biologically related parents; an evocative kind, through responses elicited by individuals from others; and an active kind, through the selection of different environments by different people. The theory adapts the 3 kinds of genotype-environment correlations proposed by Plomin, DeFries, and Loehlin in a developmental model that is used to explain results from studies of deprivation, intervention, twins, and families.