In a prospective longitudinal study of 354 parents and their first-born infants the association between parental psychopathology and risk for maladjustment in the offspring was investigated. At age two infants of disturbed parents displayed significantly poorer language performance and had higher scores of behaviour problems as compared to infants of healthy parents. While maternal disorder affected both cognitive and social-emotional outcome, the impact of paternal disorder was confined to cognitive functioning. The poorest outcome was found in infants of mothers with a personality disorder or with alcohol abuse. The relationship was maintained even after accounting for a number of family risk factors associated with parental psychopathology. One mediating factor between maternal disorder and infant maladjustment was found in disturbed mother-infant interaction. Maternal mental health did not only affect infant outcome, but was itself influenced by infant adaptation.