Abstract This study aimed to test the effectiveness of the Maternal Participation Program (MPP) on growth and neurobehavioral development of preterm infants. The hypothesis was that preterm infants whose mothers were in the experimental group demonstrated better growth and neurobehavioral development than the control group Double-blind randomized control trial evaluated 50 mothers whose preterm infants were hospitalized in the neonatal intensive care unit, a university hospital. Mothers were randomly assigned into two groups (experimental group = 25; control group = 25). The experimental group received the usual nursing care and the MPP, and the control group received only the usual nursing care. Preterm infants in the experimental group showed significantly higher weight gains, weight gain velocity, and growth velocity between 14 and 28 days after birth; as well as better neurobehavioral development at days 14 and 28. The effectiveness of the MPP to promote the growth and neurobehavioral development of preterm infants was proven.