This study addressed the assessment and treatment of high-rate self-injurious behavior in a child who was blind and deaf. The frequency of self-injury was assessed within different environmental conditions to identify potential influences on the behavior. Effective treatment was demonstrated in the form of a simple response interruption procedure that entailed physically blocking self-injurious behaviors. Subsequently, treatment was generalized successfully throughout the child's waking hours. The study provides an example of nonaversive treatment of a serious behavior disorder and the use of a functional assessment methodology to determine treatment selection.