In the Finnish Adoption Study, a national sample of adoptees with high versus low genetic liability for schizophrenia spectrum disorders was indexed by DSM-III-R diagnoses of their biological, adopting-away mothers. The rearing-family environments of the adoptees were independently evaluated from global ratings of directly observed adoptive family relationships. The interaction of high genetic liability and dysfunction of the rearing families predicted highly significantly to schizophrenia spectrum disorder of the adoptees at 21-year follow-up. Either low genetic liability or healthy rearing protected against a spectrum outcomes for the adoptees. Initial adoptive parent diagnosis, as a proxy for rearing family dysfunction, predicted to adoptee outcome only as a trend.