A Phase III randomized clinical trial (RCT) will be performed using a crossover design and employing an exoskeletal-assisted walking intervention. The experimental arm will be compared to a usual activities (UA) arm, as the control, in 64 persons with chronic SCI (>6 month post injury) who are wheelchair-dependent for outdoor mobility in the community. The WALK arm will consist of supervised exoskeletal-assisted walking training, three sessions per week (4-6 h/week) for 36 sessions for their second 12-week period. The UA arm will consist of identification of usual activities for each participant, encouragement to continue with these activities and attention by study team members throughout the 12-week UA arm. These activities will be recorded in a weekly log. The investigators hypotheses are that 1) this exoskeletal intervention will be successful in training ambulatory skills in this patient population, 2) the exoskeletal intervention will be better than a control group in improving body composition, bowel function, metabolic parameters and quality of life in the same population.