Intrathoracic tracheomalacia is characterized by increased compliance of the central airway within the thorax. This leads to excessive dynamic collapse during exhalation or periods of increased intrathoracic pressure such as crying. Extrathoracic tracheomalacia involves dynamic collapse of the airway between the glottis and sternal notch that occurs during inhalation rather than exhalation. The tone of the posterior membrane of the trachea increases throughout development and childhood, as does the rigidity of the tracheal cartilage. Abnormalities of airway maturation result in congenital tracheomalacia. Acquired tracheomalacia occurs in the normally developed trachea due to trauma, external compression, or airway inflammation. Although tracheomalacia can be suspected by history, physical examination, and supportive radiographic findings, flexible fiberoptic bronchoscopy remains the "gold standard" for diagnosis. Current treatment strategies involve pharmacotherapy with cholinergic agents, positive pressure ventilation, and surgical repair.