These models of punishment are categorized as moralistic, retributive, restitutive, deterrent, and functional. All models subscribe to a goal of maintaining social order, but not all verify the achievement of this goal. Very popular models involving the experience of pain include the moralistic, retributive, and the deterrent. The psychological functional model of punishment uses principles of behavioral psychology to change antisocial behavior. It avoids moralistic issues, guilt, shaming, revenge, and willful and purposeless aversive stimulation. A look at a sample of sexual offenders in Canadian correctional institutions reveals that modified assertive training methods (based on the functional model) should be used to help these offenders change their inappropriate sexual behavior. 2 references and 2 tables.