Kinematics of the neck are important biomechanical responses to whiplash in rear impacts. This study evaluates neck displacements of 10 volunteers, BioRID P3 and Hybrid III from JARI sled tests at 8.6 km/h with a standard seat and 9.3 km/h with a rigid seat. film analysis determined the rotation, and x- and z-displacement of the occipital condyles (OC) with respect to T1. For the volunteers, average and standard deviations were determined and cross-plotted as OC rotation versus x-displacement, and z-versus x-displacement of OC-T1. These responses provide corridors for the natural range of neck motion in rear impacts. For these parameters, BioRID P3 and Hybrid III closely simulate the volunteer neck kinematics. Tests of the Saab SAHR and standard head restraints showed differences in neck displacements that are consistent with field whiplash rates. A Neck Displacement Criterion (NDC) has been proposed to assess whiplash risks. By using the BioRID P3 and Hybrid III responses in sled tests and knowing the field whiplash rates for the Saab SAHR and standard head restraints, initial working targets for NDC are proposed for consideration.