The study tests the hypothesis that, in persons with chronic lower extremity hemiparesis, 6 weeks of seated ankle robot training will improve paretic ankle motor control with major improvements in standing balance and moderate improvements in gait, whereas the same amount of training on the treadmill with the ankle robot will improve gait function more than balance. Both robot-trained groups will outperform the treadmill only group on balance, while the treadmill + robot group will make the greatest gains in gait and the seated robot group will make some improvement in gait but will show greater gains in ankle motor control and balance.