We will develop a robust and flexible measure of postural stability that reflects the importance of subtle features of movement in postural control and the maintenance of stance. We will ensure our innovation addresses the specific needs for assessment of balance control within clinical markets related to neurology, physical therapy, and occupational therapy. The measure can be applied in conditions ranging from quiet stance to activities involving smooth movement of the body. It can be applied in isolation or during activities of daily living, and the measure is applicable to data gathered using several common instruments including force plates, accelerometers, and motion tracking systems. Phase I activities will implement a laboratory prototype. Phase II activities will reveal its sensitivity to recovery of function in postural control systems, especially as this relates to balance rehabilitation. This will allow the use of the measure to monitor clinical intervention practices and patient status. Ultimately the innovation will enhance the understanding of the effects of aging, injury, and task constraints on the physiological systems of the body by providing a bridge between quantitative measures of balance disorders and qualitative assessment of their impact on the activities of daily living and the quality of life.