Project Summary Preterm delivery occurs in 10% of all births in the United States and is the most common cause of impaired lung growth and development, decreased lung function, increased respiratory morbidity, and increased health care costs throughout childhood. There are currently no known therapies to stimulate lung growth, improve lung function, and decrease respiratory morbidity after preterm birth. The application of continuous positive airway pressure (CPAP) early after a preterm birth is the standard of care to stabilize and maintain lung volumes, avoid intubation, and decrease rates of bronchopulmonary dysplasia in the neonatal intensive care unit (NICU). Although early application of CPAP has been well studied, there is little evidence defining the optimal time to discontinue CPAP in stable convalescing preterm infants. Early use of CPAP may benefit the preterm lung by minimizing injury; however, our preclinical and clinical data strongly suggest that mechanical stretch of the lung from CPAP may stimulate lung growth and development. The primary aim of this randomized single center study is to establish that 2 additional weeks of CPAP in the NICU for stable preterm infants increases alveolar lung volume and lung diffusing capacity at 6 months of corrected age compared to infants who had CPAP discontinued as per standard care. Patients will be randomized when they fulfill specific published CPAP stability criteria for CPAP discontinuation. This research has great public health significance for its potential to change the standard of respiratory care in the NICU, and minimize the adverse effects of premature birth upon lung growth and development.