Walters and Grusec (1977) concluded that punishment is necessary for behavioral change. They define punishment as a stimulus that reduces the future probability of a behavior that occurred prior to the stimulus. Their review of animal and human research on punishment effects found that human behavior is most likely to change positively when punishment is moderately intense, administered by a friendly agent, applied over a long period, consistently applied following the targeted behavior, and not indiscriminately applied to other behaviors. One implication of these findings for crime control is that society can control behavior through peer groups and families that consistently punish unacceptable behaviors. The police can be most effective by devoting their efforts to clearing crimes as quickly as possible after their occurrence and enforcing the law consistently. The courts can most effectively control crime by eliminating plea bargaining, reducing the time between the crime and punishment, and dispensing consistent sentences. Corrections can help change criminal behaviors by placing offenders in peer groups that punish antisocial behavior consistently and appropriately. Nine references are listed.