The understanding of the incidence, epidemiology, etiology, and pathophysiology of pediatric cardiac arrest has evolved greatly in the past two decades. This includes recognition that cardiopulmonary resuscitation delays in cardiac arrest are especially injurious, ventricular arrhythmias are not as uncommon in children as previously believed, and four distinct phases of cardiac arrest can be delineated. Performance of, and technologic advances in, the treatment of cardiac arrest make this an exciting time in the field.