A cohort of 129 infants with birth weights less than or equal to 1250 gm was followed for more than 4 1/2 years (mean +/- SD: 60 +/- 10 months) to determine the independent effects of two medical risk factors--intracranial hemorrhage and severe chronic lung disease--and a parenting risk factor (abuse or neglect) on neurodevelopmental outcome. In infants without any intracranial hemorrhage or parenting risk factors, severe chronic lung disease was not related to neurologic or cognitive outcome. Infants with increasing grades of intracranial hemorrhage had increasing rates of neurologic and cognitive abnormalities. However, the factor associated with the highest incidence of later abnormality was the parenting risk factor. We conclude that infants with medical risk factors may have additional social risk factors, and that both of these influences must be considered in an examination of the long-term sequelae of neonatal complications.