Empirical evidence from this study supports the hypothesis that Tai Chi practice can improve senior citizens’ dynamic balance control and rapid-aiming arm movement performance. Of 38 senior citizens, 28 (M = 78.8 years. SD = 2.1) chose to practice the 24-form simplified Tai Chi. The remaining 10 seniors (M = 79.2 years. SD = 1.9) selected a locomotor activity (walking or jogging). Dynamic balance tests and ballistic-aiming arm movements were conducted for all participants at the beginning, middle (4th week), and end of the 8-week exercise program. The Tai Chi participants improved their time on balance more than did their counterparts who performed locomotor activities. In addition, Tai Chi practice improved arm movement smoothness to a greater extent than the locomotor activities. However, no changes in arm movement speed were observed in either group. The results suggest that Tai Chi practice may help senior citizens improve dynamic balance control and gain smoothness in rapid-aiming arm movements.