To improve child survival, efforts have to focus on improving the quality of inpatient newborn care. Inpatient care for sick newborns depends on nurses who provide care round the clock. Despite their central role in nursing hospitalized sick newborns among the literature reviewed, there is no research in Africa to understand their health care needs; their perceptions of what constitutes quality inpatient newborn care; compared views of nurses from different sectors despite a limited and poor-quality evidence base regarding their comparative performance. The main aim of this study was to explore and understand factors contributing to nurses’ ability to provide quality care of inpatient sick newborn babies in the public (henceforth referred to as Kweche), faith based [herein referred to as Teleka and private (henceforth referred to as Chiriku) health hospitals in Nairobi County. Specifically, the researcher sought to: (1) describe the context of newborn care delivery and (2) to explore nurses’ views about a good work environment (3) capacities necessary for a nurse to provide quality inpatient newborn care and to (4) assess how health sector influences nurses’ perceptions. The researcher used an ethnographic approach which involved in-depth interviews with 29 nurses, a review of newborn admission registers and quality documents, negotiated interactive observation, participation in numerous unsolicited conversations. Findings show that nurses in newborn wards of Kweche, Chiriku and Teleka hospitals in Nairobi work in markedly different structural and organisation contexts. Despite the variation in context, nurses perceive a good health working environment, and a nurse with both training and personal attributes as having the necessary capacities to provide quality inpatient care. With the current global commitment to improving quality of care in order to achieve universal health coverage, health systems in low and middle income settings need to prepare their facilities as well as their health care workers for and to provide quality care. Strategies to improve facility-based care for newborns will need to consider substantial deficits in resources and supportive work environment as part of long-term planning to improve service delivery.