This study sought to determine the effects of therapeutic horseback riding on the balance of eight individuals with mental retardation. The subjects were initially tested on four standing balance items and six quadruped balance items. Next, 6 months passed with no intervention. The intention of this time lapse was to use the subjects as their own control. After this delay, the subjects were tested again using the same procedure as in the initial testing. They were then involved in a 6-month therapeutic riding program designed to provide vestibular stimulation in a variety of ways, with the horse’s movement as a base. A third identical testing session occurred at the end of the therapeutic riding program. The results of the study showed that significant improvement was seen on standing and quadruped balance after the therapeutic riding program. It is concluded that if programming goals for individuals with mental retardation include improved balance, then therapeutic riding may be beneficial to those goals.