This study was a multicenter, prospective cohort study to define postnatal longitudinal growth for very low birth weight (VLBW) infants. The objectives were: 1) to develop postnatal growth curves for VLBW preterm infants that would permit an assessment of growth velocity; 2) to relate growth velocity and nutritional practices (duration of parenteral nutrition, age at first enteral feeding, and age at full enteral feeding); 3) to compare growth velocity in infants who are small-for-gestational age (SGA) with infants who are appropriate-for-gestational age (AGA); and 4) to relate growth velocity to several common, major morbidities, including chronic lung disease (CLD), nosocomial infection (or late-onset infection) and necrotizing enterocolitis (NEC). These growth data may be useful in identifying preterm infants who are growing slowly despite current nutritional support and in designing and performing clinical trials of nutritional interventions.