This is a randomized, double-blind, placebo-controlled, multi-center study. Three specific hypotheses will be tested: 1) iNO reduces the incidence of CLD; 2) iNO reduces serum and lung (tracheal aspirate) markers of inflammation; and 3) iNO does not increase the incidence of intraventricular hemorrhage in premature neonates. The primary endpoint is survival without CLD (defined as continued oxygen requirement) at 36 weeks post conceptional age.