As neonatal care has advanced and more immature infants are admitted to the neonatal intensive care unit, we must reevaluate fundamental management practices originally developed for infants born at later gestational ages. Studies have investigated the use of various incubator humidification levels in the care of preterm infants of older gestational ages, but evidence regarding management of ambient humidity for infants born at <25 weeks' gestation using contemporary technology is limited. Uncertainty about the best approach to incubator humidification is reflected in major variation in practice around the world. This article summarizes existing evidence about the use of humidity in incubators and its relationship with neonatal skin maturation, fluid management, temperature regulation, and morbidities. It also describes approaches to starting humidification, duration of humidification, and reducing humidification over time. It concludes with a list of important questions requiring future research.