OBJECTIVE To identify relationships between neonatal factors including conditions and treatments, nurturing environment, and psychosocial development of children born at very low birth weight (VLBW). METHODS In this longitudinal study, the medical records of 113 VLBW infants were examined, and the children were then followed up at 18 and 36 months of age. Their developmental quotient (DQ) was assessed using the Kyoto Scale of Psychological Development (KSPD), and their parents were asked about their own health, financial situation, education, and family support. Pearson's correlation and stepwise multiple regression analyses were used to explore relationships between DQ, potentially significant predictors on the KSPD, and nurturing environment. RESULTS DQ at 18 months was associated with the following neonatal factors: mechanical ventilation days (β = -.241, p = .020), Apgar score at 5 min (β = .278, p = .005), periventricular leukomalacia (β = -.218, p = .006), and treatment for retinopathy of prematurity (β = -.171, p = .048) (adjusted R2 = .32). DQ at 36 months was associated with the following neonatal and parenting factors: mechanical ventilation days (β = -.354, p < .001), periventricular leukomalacia (β = -.207, p = .009), sex (β = -.199, p = .011), mother's educational background (β = -.304, p < .001), mother's health status (β = -.159, p = .042) (adjusted R2 = .35). CONCLUSIONS These findings suggest that in addition to neonatal clinical parameters including conditions and treatments, the nurturing environment after discharge from the neonatal intensive care unit influences the psychosocial development of VLBW infants.