When used, the word punishment suggests a multitude of images. In this chapter, the image addressed and discussed from a psychological perspective is the disciplining and punishing of children. The effects of punishment on children and the role of punishment in changing behavior have only been examined from a scientific perspective since the early 20th century. However, as the role of early child rearing and early learning experiences in the development of antisocial and aggressive behavior has become more apparent, the role of punishment in suppressing or stimulating aggressive and antisocial behavior has become more controversial. Two themes are examined in this chapter. First, that punishment often has both stimulating and suppressing effects on aggressive and antisocial human behavior, and the long-term consequences of punishment may not always turn out as intended. The second and related theme is that many common assumptions that the public and criminal justice authorities make about the effects of punishment are not well supported by psychological analyses of punishment. The chapter reviews the development of antisocial behavior, psychological theory and the learning of aggressive and antisocial behavior, principles of operant conditioning and punishment, the use of punishment to modify behavior, generalized effects of punishment, a psychodynamic approach to punishment, the role of punishment in child development, and the implications of punishment of adult criminals. It is concluded that punishment may have some appropriate role in behavior management, however it must be applied wisely and carefully. Careful application may assist in changing children’s antisocial behaviors, but there are serious possibilities that it may increase antisocial behaviors instead. From a psychological perspective, there is little reason to believe that any kind of punishment by itself has much of a chance to change an offender’s behavior or deter future offenses unless it is viewed by the offender as an almost certain consequence of the behavior. Bibliographic review and references