Stereotypic behavior exhibited by a third grade boy with autism was maintained by automatic reinforcement and occurrences of stereotypy were brought under stimulus control. The intervention consisted of pairing a green discriminative stimulus card (SD) with free access to stereotypy and a red card (SD absent) with vocal redirection and blocking stereotypy. After exposure to discrimination training, the student rarely engaged in stereotypy with the SD card absent, but he almost continuously engaged in stereotypy when the SD card was present. Experimental control over stereotypic behavior was demonstrated via a combination of within session sequential alternating treatments design and withdrawal design across sessions. (Contains 3 figures.)