This study compares the thoracic deformation response of the 50th percentile male THOR NT frontal crash dummy and the response of the THOR modified with the SD-1 shoulder (THOR SD-1) relative to the thoracic response of eight 50th percentile male PMHS. The prototype Chalmers University SD-1 shoulder was designed to be more human-like in terms of geometry and range of motion in comparison to the standard THOR NT shoulder. The dummies and PMHS were restrained by a three-point restraint in a driver-side configuration and were subjected to a simulated 40 km/h frontal crash. The most prominent difference between the responses of the dummies and PMHS involved motion of the lower right anterior ribcage measurement site that is the farthest lateral distance from the diagonal shoulder belt. During the impact event, this site moved substantially anteriorly and away from the spine for the PMHS. The PMHS lower right “bulge out” behavior is believed to be caused by inertial loading of the ribcage, underlying organs, and soft tissue overlying the torso. The THOR SD-1 shoulder altered the shoulder belt position relative to the thoracic deflection measurement sites resulting in a different distribution of deformation for the upper measurement sites although the average upper site deformation was similar to that recorded for the standard THOR shoulder.