Motor measures are sensitive to central lesions, but they are also affected by peripheral injury and motivation. The motor skills profiles of proven brain injury clients were compared with the profiles of healthy postconcussion patients. The chief result was a double dissociation: The traumatic brain injury (TBI) group produced a motor dysfunction gradient consistent with upper motor neuron disease, while the compensation-seeking postconcussion group produced a nonphysiologic pattern. Objective measures of behavioral pain and emotional distress did not correlate with the findings. Motor skill deficiencies in postconcussion syndrome (PCS) are probably functional in nature. (JINS, 1996, 2, 477–485.)