Abstract: Although coordination has been identified as a fundamental element necessary for the successful achievement of walking, this aspect of gait has yet to be embraced into instrumented gait analysis, perhaps in part due to the lack of a normative reference and unfamiliarity of mathematical methods that are best suited to capture this essential behavior. Therefore, this work focused on expanding clinical gait analysis techniques by validating nonlinear methods that describe the influence of neurological control on the musculoskeletal system. This body of work investigated the coordination dynamics during gait in both prospective and retrospective subjects free of gait pathology, subjects with spastic cerebral palsy, and subjects with a lower limb amputation using motion capture and mathematical models to help elucidate the complexities of gait and enhance therapeutic interventions. This investigation quantified coordination strategies employed by an unimpaired subject when presented with various walking conditions and challenges mimicking various inhibitions associated with performing the task of swing limb advancement. Two novel indices of coordination dynamics were created to provide a concise metric and ease their inclusion into future research applications. The first normative reference dataset of these coordination measures was created from a large cohort of unimpaired subjects. While there is presently not a gold standard method for quantifying coordination during gait, the exciting correlations between the proposed measures and select clinical performance tasks indicate the coordination measures quantify essential inter-segmental coordination dynamics of walking. The theoretical pendular software model created shows swing limb advancement is not a purely passive motion, but instead an actively controlled motion. Comparisons between the various cohorts revealed the proposed measures of coordination are more suitable for characterizing motor control strategies contributing to a gait pattern, quantify organization of individual segments, identify mechanisms of change, and reveal the loci of impairment(s). The proposed measures of coordination dynamics are capable of distinguishing between different gait pathologies and patterns associated with altered limb advancement during the swing period of gait. Results from this multidisciplinary work have the strong potential to directly impact the clinical treatment of persons with aberrant coordination dynamics during gait.