In a prospective study, the cognitive, language, and motor development of 80 very low birth weight infants (> 1,501 grams) was compared with that of 68 full-term infants, matched on social class, sex, parity, and maternal age. When the scores were not corrected for the degree of prematurity, the preterm infants, with the exception of the SGA (small-for-gestational age) singletons, had significantly lower cognitive (Bayley MDI), language (Reynell), and motor (Bayley PDI) scores at 2 years of age. When the scores were corrected for prematurity, only the motor development scores of the preterm AGA (appropriate-for-gestational age) group were lower than those of the full-term group. Using a system of demographic, perinatal, and reproductive variables, the cognitive, motor, and language development of these infants at 2 years could be predicted with a high degree of accuracy, and infants with delayed development could be detected. Factors important in predicting developmental functioning and delay included socioeconomic status, parental educational level, maternal cigarette smoking, number of previous pregnancies, and in the preterm infants, apnea, birth asphyxia, and severity of respiratory distress. This model appears to be a promising one for the detection of infants at risk for developmental problems