UNLABELLED The purpose is to examine the infant feeding beliefs and day-to-day feeding practices of NICU nurses with the goal of identifying ways to improve breastfeeding promotion. DESIGN AND METHODS An ethnographic approach incorporated 14 months of participant observation and interviewing. General informants consisted of 114 purposively selected NICU nurses from a northeastern, level-IV NICU, pediatric hospital. From this group, 18 nurses served as key informants. There was an average of 13 interactions with each key informant and 3.5 with each general informant. Audio taped interviews and observational field notes were gathered for descriptions of beliefs and practices. Data were coded and analyzed for patterns and themes with the aid of NUD*IST. RESULTS 1. The nurses identified health benefits of breastfeeding, but spoke in greater detail and with more emotion about day-to-day challenges of breastfeeding in the NICU. 2. Formula feeding evoked less emotion and most nurses viewed it as safe and convenient. 3. Despite infant feeding challenges in the NICU, nurses who had breastfeeding continuing education and/or some positive experiences with breastfeeding: identified evidence based breastfeeding benefits for mothers and babies; emphasized the health-based differences between breast milk and formula; and were more committed to working through difficulties with breastfeeding. CONCLUSIONS Breastfeeding promotion interventions should include every NICU nurse and incorporate both evidence-based and affective components to overcome day-to-day feeding practice challenges. PRACTICE IMPLICATIONS Breastfeeding promotion interventions must address conflicting and emotionally evocative infant feeding beliefs of NICU nurses. Effective interventions must be integrated within the realities of bedside feeding practices.