Ultrasonographic evaluation of the lung was historically perceived as challenging or near-impossible, as air-filled structures scatter sound. In the past few decades, point-of-care ultrasound (POCUS) of the lung has demonstrated increasing value in the assessment of patients with pleural or pulmonary conditions. The diagnostic performance of POCUS compares favorably to chest radiography for a wide array of conditions, while allowing more rapid assessments at the bedside and reducing radiation exposure. Topics covered in this chapter include pulmonary edema, pneumonia, pneumothorax, pleural effusion, rib fracture, acute respiratory distress syndrome, and interstitial lung disease.