 Multi-center, double blind, placebo-controlled, randomized clinical trial. Infants who meet all enrollment criteria at any point during days 5 to 14 after birth will be randomized to inhaled NO starting at 20 ppm, or matching placebo, by means of a blinded INOvent delivery device. All infants will receive 24 days of therapy, following a dose reduction schedule. Infants who are extubated before 24 days will continue therapy via nasal continuous positive airway pressure CPAP or nasal cannula to complete 24 days of therapy. The primary outcome measure will be survival without BPD at 36 weeks gestational age using a physiologic assessment of BPD. 