Although thoracic injuries occur less frequently in children than adults, they remain a source of substantial morbidity and mortality. Disparate problems such as rib fractures, lung injury, hemothorax, pneumothorax, mediastinal injuries, and others may present in isolation or in combination with one another. Knowledge of the manner in which pediatric anatomy, physiology, and injury patterns change with age may expedite the evaluation of the pediatric chest after trauma. Differences in pulmonary functional residual capacity, blood volume, chest wall and spinal soft-tissue mobility, and cardiac function may translate into problems or benefits of important consequence. For example, although more predisposed to hypoxemia, young children may remain well compensated hemodynamically, despite significant blood loss. Rare injuries in children, such as cardiac and great vessel trauma, may remain undiagnosed precisely because of their scarcity and protean symptoms.