This chapter aims to review the behavior modification procedures used and the results obtained in a number of studies involving the severely and profoundly retarded. Education and rehabilitation endeavors with the severely and profoundly retarded differ in several quantitative and qualitative dimensions from similar endeavors with the moderately and mildly retarded. The goals become those of developing toileting, feeding, grooming, and other self-care skills, and of developing basic works and work-related skills. Work skills, and the opportunity to use these in a simple remunerative environment, add dignity and personal worth to the life of the more severely retarded adolescent and adult. The presentation of primary aversive stimulus conditions contingent upon inappropriate behavior has been used in a number of behavior modification programs in an attempt to eliminate self-destructive, aggressive, and disruptive behaviors. Elimination of this highly disruptive behavior and development of peer social interaction were identified as the treatment goals.