The high rate of abdominal injuries, particularly in children, related to loading of the seatbelt in automotive impacts demands that crash dummies exhibit better biofidelity. Motivated by field data, Elhagediab et al, in 2007, constructed a silicone gel-filled abdominal insert for the Hybrid III six-year-old dummy to improve its biofidelity under a variety of loading conditions and sample pertinent data for the assessment of injury risk. These tests aimed to assess the biofidelity of the pediatric abdominal insert by comparing its loading response to that of the porcine pediatric abdomen model developed by Kent et al in 2006. In the same test fixture and under the same loading conditions, in-situ in the Hybrid III dummy, the abdominal insert was belt-loaded across the abdomen at three different velocities, two different belt angles, two different penetration depths, and both with a neoprene jacket and without the jacket. High speed video of each test as well as reaction force, belt force, acceleration at the belt midline and on the tabletop, as well as a dummy outputted chest deflection and lumbar forces were recorded. The data was analyzed and compared to Kent’s porcine model in order to assess the biomechanical response of the abdominal insert. The insert was found to match the porcine model kinematics and rate insensitivity, but the overall stiffness was too compliant and the insert lacked the same inertial response at the onset of loading characteristic of the porcine model.