A nine-month study was conducted under the direction of Tank-Automotive Research, Development and Engineering Center (TARDEC) in Warren, MI. to determine the best platform design for inherent all-terrain mobility of an unmanned robotic vehicle in the 15000-2500 lb. range. Reference platforms were the DEMO III 4x4 and the Utah State University 6x6 with omni-directional wheels. The study systematically developed desired top- down design-driving capabilities, operational needs, and mobility concepts supported by extensive analysis using the NATO Reference Mobility Model and literature searches. Maximizing mobility over all terrain and resisting immobilization were emphasized in order to minimize sensor computational burdens while maximizing the probability of timely mission accomplishment. Several wheeled, tracked and hybrid platform concepts were evaluated. Significant improvements in cross- country mobility, obstacle negotiation and self-extraction capability were achieved with hybrid solutions. Final concept development focused on an 8x8 swiveling wheeled platform with band track overlays. Conclusions of the study were: a technology demonstrator platform should be built for mobility validation and NRMM II refinemment; a robotic- vehicle-specific NRMM II mobility scenario should be developed; and sensor solutions for unmanned mobility platforms should be revisited.