Mark is a 7 year old with severe mental retardation and self-injurious behavior. The behaviors include hitting his face with his fist and banging his head against the wall, floor, or table. These behaviors occurred intermittently in the past. During the past 6 months, they have increased in frequency and intensity and caused bruising and swelling of his forehead. The behaviors have occurred in both the home and school environment, but seem to be more frequent and intense at home. Mark's parents state that occasionally the behaviors occur when Mark is so frustrated that he can't do something that he wants to do, but more frequently they occur for "no reason at all." Mark could be watching TV or playing with a toy and begin head banging. His parents have managed the behavior by verbal reprimands. If that is not effective, they will hold Mark to prevent him from hitting himself or move him onto his bed with pillows against the wall. These procedures are very disruptive to the family now that the behavior is occurring at least a couple times on most days. Mark is not on any medications. He has not had seizures. He has had ear infections and constipation in the past and was treated for gastroesophageal reflux as an infant. He sleeps 9 hours each night without snoring. There has been no change in his appetite or sleep. His parents estimate that he has about 20 words that he uses communicatively. Mark lives at home with both parents and 2 younger siblings. For the past 2 years, he has attended the same life skills class with 8 students, a teacher and 2 assistants. Mark's mother had postpartum depression after the birth of his 5-year-old brother. The physical examination does not demonstrate any change in his growth percentiles. The skin on the right side of his face is erythematous as he was hitting it prior to the examination. There is no sign of otitis media.