The incidence of bronchopulmonary dysplasia (BPD), defined as oxygen need at 36 weeks of postmenstrual age, is about 30% for infants with birth weights <1000 g. BPD is associated with persistent structural changes in the lung that result in significant effects on lung mechanics, gas exchange, and pulmonary vasculature. Up to 50% of infants with BPD require readmission to the hospital for lower respiratory tract illness in the first year of life. Long-term measurements of lung function in BPD include normalization of pulmonary mechanics and some lung volumes over time as somatic and lung growth occur, whereas abnormality of small airway function persists. The majority of data reveals no long-term decrease in exercise capacity. Mild to moderate radiological abnormalities persist. BPD is a result of dynamic processes involving inflammation, injury, repair, and maturation. Infants with BPD have significant pulmonary sequelae during childhood and adolescence, and continued surveillance of young adults with BPD is critical.