Although many family therapy programs have taught behavior modification techniques to parents, few have involved siblings as therapeutic agents in the treatment of retarded, emotionally disturbed, or physically handicapped children. The authors describe their experiences with two families in which siblings were taught to use simple procedures to encourage desired behaviors in a disturbed brother or sister. They conclude that further investigation is needed to refine sibling training techniques and suggest that involvement in treatment programs may have beneficial influences on the normal siblings of disturbed children.