The dynamic response of the human head is investigated using experimental data and analytical simulations. The head acceleration response is characterized from experiments on seated human cadavers subjected to frontal, occipital, and side head impacts. Acceleration time histories at the head vertex and at the front/occiput/side of the head are presented for measured force time histories and impact velocities. Response results from a detailed multi-degree of freedom model, incorporating inertial and constitutive properties of the head-neck system, are also presented. Finally, head injury criteria are discussed on the basis of experiments and model analysis.