Behavioral characteristics of very low birth weight infants (<1,501 gm) were determined with the term Brazelton Neonatal Behavioral Assessment Scale and Selected items from a preliminary form of the scale for premature and at-risk infants. The behavior of 188 infants was assessed at a time as optimal as possible for social interaction. Our very low birth weight infants were upset less easily, had several reflexes with below average scores, and were less responsive to visual stimuli than term infants of other studies. Improved description of interactive abilities and tolerance of the testing procedure was made possible with some items from the preliminary premature scale. Orienting responses in 6 infants tested after 44 weeks because of prolonged illness were less than optimal with a single exception. This suggests that behavioral capacity, not age, should define where the Brazelton scale is not applicable.Perinatal factors including birth weight, gestational age, and age that weight gain began, predicted some motoric and state control responses. Whether this predictive capacity will persist or change with time awaits results of follow-up of these infants.