The Naval Biodynamics Laboratory (NBDL) has collected a database which describes human dynanic responses for −X acceleration exposures as a function of mass distribution variations of the head. Kinematic responses were measured on subjects with, (a) no mass addition; (b) with a helmet and weight-carrier mass addition; (c) and with the helmet and added weights symmetrically located with respect to the mid-sagittal plane of the head. The total mass addition to the head with the weights was approximately 30 percent. The helmet and weights were positioned with reference to the head anatomical coordinate system for each subject, with mass moments of inertia and variations in center of gravity then being determined. This paper compares responses both as a function of a mass distribution parameters and as a model to simulate the observed responses. The maximum resultant force at the occipital condyles was found to be proportional to the product of the non-inal impact acceleration and the sum of the head and added mass.