The objective of this study was to develop a valid and reliable discriminative index that measures parent satisfaction with the medical care of their infant in the NICU. We developed an initial questionnaire (Item Reduction Questionnaire) by reviewing the literature, surveying 63 NICU clinicians, and interviewing 125 parents of infants in 2 tertiary level NICUs regarding what they liked and disliked about the medical care of their infants. We administered the Item Reduction Questionnaire, which included 154 items, to 60 parents, who rated the frequency and importance of these items. We included the items identified most frequently as sources of dissatisfaction and rated most important in a second, briefer instrument, the Neonatal Index of Parent Satisfaction (NIPS). To measure reliability we administered the NIPS to 47 parents twice, separated by a 1-week interval. We assessed validity by comparing actual to predicted correlations between NIPS scores and other measures: parent's global rating of satisfaction, medical caregiver ratings of mother's satisfaction, medical caregiver ratings of father's satisfaction, and parents' perception of their infant's health status. We also compared mean NIPS scores for parents who did and who did not report incidents when errors occurred in the medical care of the infant. Of 154 items generated, we included 27 in the NIPS. The intraclass correlation between two administrations of the NIPS to the same 47 parents was 0.71. As predicted, there was a high correlation (0.61) between the NIPS score and parent global rating of satisfaction, and much lower correlations with other variables. Mean NIPS scores for parents who did and who did not report errors differed significantly (difference, 14.6; 95% CI around difference, 5.8-23.5; p < 0.001). The NIPS is likely to be a useful measure for discriminating between parents who differ in terms of their satisfaction with the medical care of their infant in the NICU.