Some children exposed to socioeconomic (SES) deprivation are resilient and function better than expected, given the level of deprivation they have experienced. The present study tested genetic and environmental contributions to young children's resilience and vulnerability to SES deprivation. Children's resilience was assessed by the difference between their actual score and the score predicted by their level of SES deprivation in the E-Risk Study, an epidemiological cohort of 1,116 five-year-old twin pairs. Consistent with previous research, results showed that maternal warmth, stimulating activities, and children's outgoing temperament appeared to promote positive adjustment in children exposed to SES deprivation. Findings add new information by demonstrating that resilience is partly heritable and that protective processes operate through both genetic and environmental effects.