The role of punishment in the psychiatric in-patient treatment of nonpsychotic latency-age children with behaviourdisorders is discussed. Punishment is defined as the removal of previously existing positive reinforcers or the administration of aversive stimuli. Ways in which appropriate social behaviour may be acquired are briefly considered. These include reinforcement of desirable responses, non-reinforcement of undesirable responses, reinforcement of incompatible responses and imitative learning. The reported effects of punishment on behaviour are reviewed and the psychological functions necessary before punishment can have the intended effects considered. For seriously disturbed children punishment is ineffective as a treatment technique. It reinforces pathological perceptions of self and adults even if it successfully suppresses behaviour. The frame of reference of the seriously disturbed child contraindicates the removal of positive reinforcers and verbal as well as physical aversive stimuli. Controls and punishments must be clearly distinguished. Controls continue only as long as the behaviour towards which they are directed. They do not include the deliberate establishment of an unpleasant state by the adult as a result of particular behaviour. Control techniques such as removal from a group may be necessary but when possible should be avoided in favour of techniques less likely to be misinterpreted. Avoidance of punishment in treatment makes even more important explicit expectations and provision of realistic controls. Natural laws may result in unpleasant experiences as an unavoidable result of certain behaviour. By definition such results can never be imposed by the adult. Treatment considerations may necessitate that the child be protected from the results of his actions. Avoidance of punishment requires a higher staff/child ratio, more mature and better trained staff. Sometimes children have previously been deterred from serious community acting out only by punishment. Should the therapeutic endeavours outlined not prevent such behaviour, treatment in a closed setting without punishment is indicated, not the use of punishment in an open centre.