This present study sought to decrease the self-injurious behavior of a 37-month-old child enrolled in a preschool program. The subject persisted in biting and mouthing his left hand, resulting in reddening and callousing of the area between the thumb and index finger. A multiple-baseline design with a reversal component was used. In multiple-baseline fashion, restitutional and positive practice overcorrection were tried with reductions in both biting and mouthing during two separate periods of time in the preschool setting. Withdrawal and reintroduction of overcorrection, representing the reversal component, established unequivocally that reductions in the self-abusive behavior were attributed to the overcorrection treatment procedure. In a third, untreated setting—the home—no transfer of training was indicated. Strategies are offered that might result in generalized treatment effects.