In the Dundee Development Screening Programme all children born in Dundee in 1974 and 1975 were screened at intervals during infancy and childhood. The obstetric and neonatal antecedent factors in 300 of the 322 singleton children with neurodevelopmental disability (index group) were compared with those of the 600 children of normal development born immediately before and after each child with disability (control group). Low social class was associated with mental retardation, global delay, speech delay, and behavioural disorder, but not with cerebral palsy or motor delay. With the exception of cerebral palsy, strong associations were found between all categories of disability and severe hypertension, unclassified antepartum haemorrhage, and preterm uterine activity. Cerebral palsy was not associated with antepartum complications, but was with fetal tachycardia during labour. Our data suggest that neurodevelopmental disability may, in many cases, originate during pregnancy and delivery.