Debate surrounds the utility of the Biofidelic Rear Impact Dummy (BioRID) anthropomorphic test device (ATD) for providing meaningful biomechanical metrics during rear impact and the appropriate criteria for interpreting the ATD response. In the current study, we performed a comparison of the kinematic and kinetic responses of the BioRID II and Hybrid III ATDs over a range of low- and moderate-speed rear impact conditions. A BioRID II and a midsize male Hybrid III were tested side-by-side in a series of rear impact sled tests. To evaluate occupant response in rear impact, the ATDs were positioned into front row standard production bucket seats, restrained by 3-point safety belts, and subjected to rear impacts with delta-Vs (ΔVs) of 2.2, 3.6, 5.4, and 6.7 m/s (5, 8, 12, and 15 mph). To further evaluate the effects of seat/restraint design on occupant responses, the ATDs were positioned into front row seats with integrated seat belts (all-belts-to-seats) and subjected to rear impacts with ΔVs of 2.2 and 5.4 m/s (5 and 12 mph). In all test configurations, we measured head accelerations and rotation rates, upper and lower neck forces and moments, T1 accelerations, lumbar forces and moments, and axial femoral force. The kinematic and kinetic responses of the BioRID II and Hybrid III ATDs were compared across impact severity and seat conditions. Observed neck loading measures are discussed in the context of proposed and accepted injury assessment reference values.