Pneumothoraces are classified as spontaneous, traumatic, and iatrogenic. Spontaneous pneumothoraces (SP) occur without recognized lung disease (primary, PSP) or due to an underlying lung disease (secondary, SSP). Treatment of PSP and SSP has been quite heterogeneous in the United States; adoption of the recently published American College of Chest Physicians guidelines will hopefully improve care. Central to these guidelines is the emphasis of observational management of a small pneumothorax in clinically stable PSP patients, and chest tube placement as key initial management in PSP or SSP patients who are unstable or have a large pneumothorax. Traumatic pneumothoraces due to penetrating or nonpenetrating (blunt) trauma usually require the placement of a larger-bore chest tube. Iatrogenic pneumothoraces appear most commonly due to transthoracic needle aspiration and may be treated in carefully selected patients with observation. The presence of underlying emphysema in the setting of an iatrogenic pneumothorax usually mandates placement of a drainage catheter. Newer mechanical ventilation modes and strategies may limit the development of positive pressure ventilation- related iatrogenic pneumothoraces.