There have been many attempts to explain self-injurious behavior (sib). Typically sib is composed of a series of self-injurious responses (sirs) that are repetitive and sometimes rhythmical, often with no obvious reinforcers, and therefore similar to stereotyped behavior. A patient who emits sirs at high frequency and/or magnitude is particularly difficult to work with because the behavior interferes with the production of more desirable responses and there is always the risk of severe and permanent physical injury, for example, head and eye damage. Usually such patients must be physically restrained or maintained on heavy dosages of drugs. Lovaas and his colleagues successfully employed punishment in the form of painful electric shock to dramatically reduce the frequency of sirs in several schizophrenic children. The chapter describes two punishment procedures used to control sib in a psychotic boy. In Study I, punishment was withdrawal of human physical contact contingent on a sir. In Study II, punishment was response-contingent painful electric shock.