The use of nasal intermittent positive pressure ventilation (NIPPV) as respiratory support for preterm infants is well established. Evidence from randomized trials indicates that NIPPV is advantageous over continuous positive airway pressure (CPAP) as post-extubation support, albeit with varied outcomes between NIPPV techniques. Randomized data comparing NIPPV with CPAP as primary support, and for the treatment of apnea, are conflicting. Intrepretation of outcomes is limited by the multiple techniques and devices used to generate and deliver NIPPV. This review discusses the potential mechanisms of action of NIPPV in preterm infants, the evidence from clinical trials, and summarizes recommendations for practice.