This prospective survey included all infants born in the United Kingdom and Ireland during a 10-month period during 1995 at 20 to 25 weeks’ of gestation. At a median age of 30 months, the children were assessed by an independent examiner using the Bayley Scales of Infant Development and a standardized examination. Of 308 surviving children, 92% were formally evaluated by 10 experienced developmental pediatricians.Nearly one in five children (19%) had a Mental/Psychomotor Development Index more than 3 SDs below the mean and were considered to be severely disabled. Development was moderately delayed (2–3 SDs below the mean) in another 11% of children. Scores did not correlate closely with gestational age or multiple versus single birth, but boys had significantly lower psychomotor scores than girls. One in 10 children had severely disordered neuromotor function, and 14% had less severe disability. A majority of these children, who made up 18% of the study group, had a pattern recognized as cerebral palsy. Seven children, six of them treated for retinopathy of prematurity, were blind or could perceive only light. Squint and other less severe visual impairments were prevalent. Five children had profound, and 36 had less severe, hearing loss. In all, nearly one-fourth of the study cohort, 23%, were severely disabled in some way. These children had smaller head circumferences than those lacking disability. These findings indicate that children born long before term commonly have severe disability.