A precise radiologic technique for assessing the forces producing pelvic disruption has been helpful in arriving at a logical classification of pelvic injury. The radiologic examination should include anteroposterior, inlet and outlet views, as well as tomograms and occasionally computed-assisted tomographic evaluation (CT scanning). On the basis of this radiologic assessment with some biomechanical studies, a classification of three major forces producing injury is suggested. The anteroposterior and lateral compression types, while vastly different, may both have stable and unstable subtypes associated with them. The vertical shear fracture is always unstable. An accurate history and physical examination in conjunction with the above radiologic principles will lead the surgeon to a precise determination of the fracture pattern. A knowledge of the forces necessary to produce this pattern is helpful in the management of the patient with this particular traumatic lesion.