The aim of this longitudinal sibling adoption study was to estimate genetic and environmental components of variance in parent- and child-reported measures of the family environment (parental negative affect, negative control, and achievement orientation). Participants included 85 adoptive and 106 nonadoptive sibling pairs from the Colorado Adoption Project. Parents and children completed annual assessments of the family environment when the children were 10, 11, and 12 years old, and genetic and environmental parameter estimates were derived. Genetic influences were found for parent-reported negativity and warmth and child-reported achievement orientation, suggesting child genetic effects on these measures of the family environment. Shared environmental influences were found for parent-reported negativity, inconsistent discipline, warmth, and child-reported positivity. Nonshared environmental variance was substantial for children's ratings, but modest for parents' ratings.