The intellectual and functional status of a regional cohort of children who weighed 501 to 1000 gm when born between 1980 and 1982 was evaluated at a mean age of 5 1/2 years by standard psychometric tests. Of 90 long-term survivors (survival rate 49%), 78 children (87%) had the full test battery, 5 children (6%) had other tests (4 were blind), and one child was untestable. Most of the mean scores were within 1 SD of the test norms; the lowest scores were in the McCarthy Motor scale and in the Beery Test of Visual-Motor Integration. Children without neurologic impairments and those with an IQ greater than or equal to 68 (n = 60) had higher overall scores but still performed poorly on the Motor subscale and the Beery test. Children who weighed less than 800 gm at birth (n = 28) were similar to those who weighed greater than 800 gm (n = 50), except in the Memory and Motor subscales, in which they performed significantly less well. At a functional level, determined by the Vineland Adaptive Behaviour Scales, two thirds of the children were performing in the adequate range and the remainder in the moderately low to low range. Of the 43 children with no neurosensory impairments and an IQ greater than or equal to 84, 49% were identified (by the Florida Kindergarten Screening Battery) to be at mild to high risk for future learning disabilities. The data from this unselected population provide an unbiased estimate of the prevalence of intellectual and functional problems in children who weighed less than or equal to 1000 gm at birth.