Pediatric care providers are repeatedly called upon to evaluate a cyanotic newborn in the labor and delivery suite, or in the well-baby nursery. A myriad of disorders spanning all-organ systems exist as possibilities for each of these problems, although several causes for newborn cyanosis are particularly common. In this second of a three-part series, primary pulmonary disease, airway obstruction, and extrinsic compression of the lungs as causes for newborn hypoxia are explored. It is in this group of disorders that we find the answers for the greatest number of these cyanotic dilemmas. Knowledge of the breadth of diagnoses, and respect for the variety of clinical possibilities, is the first step in providing a patient with accurate diagnosis, treatment, and referral.