NHTSA identified 273 NASS rollover crashes occurring from 1997 through 2000 in which the light vehicles had more than 6 inches of residual roof crush. The agency analyzed these cases, but we have studied them in much more detail. We found a number of important, consistent features that demonstrate conditions that produce rollover injuries, and strongly indicate how rollover casualties can be reduced using readily available technologies. We found: (1) nearly two-thirds were essentially flat ground rollovers without complications; (2) the windshield was always broken when the front of the roof was damaged; (3) virtually all had major damage over an A pillar and a substantial majority had front fender damage indicating that forward pitch in at least one roof impact was roughly 10 degrees; (4) where the vehicle executed more than ½ roll, the initially trailing side of the roof generally had the greatest crush; (5) safety belt use was critical to the pattern of injuries and ejections; (6) the type of roof damage is a function of its design and the nature of the roof impacts; (7) nearly one fifth of the occupants had MAIS 3 or greater injury to the head, face, or cervical spine; and (8) when non-ejected occupants received head, neck or upper torso injuries, they were generally seated on the initially trailing side under a significantly crushed part of the roof. Our study strongly suggests which countermeasures would best address the problem of light vehicle casualties in rollovers, discusses various candidate countermeasures, and estimates the casualty reduction that would result from them. Finally, we discuss the implications for Federal policies.