ABSTRACT. This study compares the Neurobiologic Risk Score (NBRS) with developmental outcome in 199 infants ≤1500 g birth weight to determine levels of risk and to investigate the relative contributions of the NBRS and nonmedical factors to developmental outcome. The NBRS correlated significantly (p < .0001) with the Bayley Mental (MDI) and Psychomotor (PDI) Indexes, and neurologic examination score (NS) at 6, 15, and 24 months. Three risk groups were identified: low, NBRS ≤4; intermediate, NBRS 5 to 7; and high, NBRS ≥8 with an incidence of major handicaps at 24 months of 7%, 32%, and 50%, respectively. Of eight factors considered, the NBRS accounted for the greatest variance: MDI, 14 to 27%; PDI, 25 to 29%; NS, 34 to 42%. Additional increments of variance were contributed by gender (MDI, PDI, NS), maternal intelligence and race (MDI), and maternal education (PDI). The NBRS is a useful tool for identifying risk for developmental abnormalities due to neonatal medical events. J Dev Behav Pediatr 14:375–380, 1993. Index terms: very low birth weight infants, developmental outcome, developmental follow-up, biologic risk, prematurity.