This study addresses the mental and motor development of 78 low birth weight infants (LBW) classified into five groups according to early medical complications: (1) respiratory distress syndrome (RDS); (2) intraventricular hemorrhage (IVH Grades I-II); (3) IVH (Grade III); (4) IVH (Grade IV) with hydrocephalus; and (5) bronchopulmonary dysplasia (BPD) with or without IVH. Each child received an assessment of mental and motor development at 6, 12, 24 and 36 months of age. Results of mental scores revealed clear effects of group and age, but no interaction of group and age. The RDS and IVH (Grades I-III) groups generally had higher scores on indices of mental development than did IVH (Grade IV) and BPD infants with or without IVH. Although most groups had higher mental scores at the older ages, rates of growth were essentially parallel across the five groups. There was some support for differential rates of motor development, with the IVH (Grade IV) group showing acceleration between 24 and 36 months of age while the BPD group continued to show motor delay at 36 months. These results call into question the common practice of correcting psychology test scores of LBW infants for gestational age.