The study of genotype-environment interaction (G x E) has been dominated by two competing hypotheses, one that heritability is greater in high-risk environments (diathesis-stress) and the other that heritability is greater in permissive environments. The current study examined relationships between verbal and nonverbal abilities and 10 measured environments, using a sample of 4-year-old same-sex twins (N=4446 children). Significant G x E emerged for verbal ability with three of the environmental indices, all in the direction of the diathesis-stress model (family chaos, instructive parent-child communication and informal parent-child communication). No significant G x E emerged for nonverbal ability. We conclude that G x E exists for verbal ability in early childhood and tends to be in the direction of greater heritability in high-risk environments.