In order to improve the developmental proficiency of neonatal intensive care unit nurses, a standardised infant positioning assessment tool and a bedside education programme were introduced to the registered nurses in a 46 bed level III neonatal intensive care unit in the western United States. A developmental positioning team collected pre-intervention positioning scores on 54 preterm infants. This was followed by a survey of the registered nurses beliefs and attitudes, the introduction of the standardised assessment tool and an informal education programme. Post-intervention positioning scores were collected on 55 preterm infants, and analysis of the data indicated there was a statistically significant change in mean positioning scores. Additionally, the registered nurses identified several barriers to the implementation of developmental positioning. This research indicates the use of a standardised infant positioning assessment tool and bedside education may be useful strategies for improving the developmental positioning proficiency of NICU nurses.