BackgroundDevelopmental support care for preterm infants contributes toward their health and shortens their hospital stay. In many countries, programs for preterm infant development such as Newborn Individualized Developmental Care and Assessment Program and Philips Wee Care have not yet been disseminated. ObjectivesTo evaluate the effectiveness of neonatal intensive care unit nurses’ competence enhancement program for developmental support care of preterm infants. MethodsA quasi-experimental study using pretest and posttest designs with a nonequivalent control group was conducted in five neonatal intensive care units of university hospitals in South Korea. A total of 39 nurses (20 in the experimental group and 19 in the control group) participated. The program was composed of family support, healing environmental support, stress and pain management, sleep support, position support, nutrition optimization, skin protection, and sensory stimulation. In addition, four sessions were provided using Zoom, Padlet, online quizzes, and performance diaries. ResultsFor nursing knowledge, no significant interaction effect was observed between groups and time (F = 1.38, p = .258). However, the main effect on the group (F = 10.81, p < .001), and the main effect of time were significant (F = 12.97, p < .001). For nursing attitude, the interaction effect between group and time (F = 2.06, p = .142), and the main effect on the group were not significant (F = 0.23, p = .635). Finally, for nursing competence, the interaction effect between group and time was significant (F = 4.46, p = .019). ConclusionsThe educational program was effective in improving nursing knowledge and competence in developmentally supportive care for preterm infants. This program is expected to contribute toward the growth and development of premature infants.