Death after injury is a worldwide epidemic. Hemorrhage as a cause of death represents the leading potentially preventable condition. Based on hard-won experience from the recent wars, and two decades of military and civilian research, damage-control resuscitation (DCR) is now widely used. This article will briefly describe the history of blood transfusion, outline "why we do DCR," and then discuss "how we do DCR." Modern DCR occurs both prehospital and in the hospital and has several main tenants. Currently, DCR focuses on the liberal use of temporary hemorrhage-control adjuncts, early use of whole blood or balanced blood product-based transfusions, mitigation of crystalloid use, hypotensive resuscitation to promote hemostasis and decrease coagulopathy, and correction of ongoing metabolic derangements, followed by rapid definitive hemorrhage control. These concepts have evolved from a series of lessons learned over time from both civilian and military trauma casualties, and DCR is now the standard of care in trauma resuscitation.