Many severely/profoundly retarded and autistic children exhibit stereotypic behaviors that interfere significantly with learning. Some of these stereotypies appear to be maintained by the sensory (e.g., auditory, visual, tactile) consequences they provide the child. This article presents a case study of a young girl who exhibited excessive handmouthing. Contingent sensory reinforcement was used to reduce her handmouthing to substantially lower levels. The intervention provided her with an altemate means of obtaining the type of reinforcement that appeared to maintain her handmouthing. The results are discussed in reference to the benefits for the child and the feasability of using the procedures in the classroom.