The acute management of potential spinal injuries in trauma patients is undergoing radical reassessment. Until recently, it was mandatory that nearly all trauma patients be immobilized with a back board, hard cervical collar, head restraints, and body strapping until the spine could be cleared radiologically. This practice is still recommended by many references. It is now clear that this policy subjects most patients to expensive, painful, and potentially harmful treatment for little, if any, benefit. Low-risk patients can be safely cleared clinically, even by individuals who are not physicians. Patients at high risk for spinal instability should be removed from the hard surface to avoid tissue ischemia. Understanding the rationale for these changes requires knowledge of mechanisms of injury, physiology, and biomechanics as they apply to spinal injuries.