The psychological factors in criminality are related to genetic and constitutional causes and to personality and other sources of individual differences. These are of critical importance in relation to both the causes of crime and its control. Antisocial behavior is the result of certain peculiarities of the brain and nervous system that interact with specific environmental factors. Criminal activity cannot be completely explained by a single theory. The three stages of the judicial process where intervention may prevent or control illegal behavior are "predelinquent," "prejudication," and "postadjucdiation." Poor motivation and resistance to change are major problems in treating or rehabilitating offenders; cognitive therapy and allowing offenders to chose their own goals and behaviors have led to most successes. Although many programs and treatments have not succeeded in markedly reducing recidivism, that does not mean that nothing will work. Individual differences are important in treatment responsiveness. Effectively reducing recidivism is often brought about by using a combination of punishment and reinforcement procedures. For punishment to be effective, it must be applied as soon after the crime has been committed as possible, and its implementation must be certain. This is often not the case. Prison terms and harsh treatment do deter criminal activity, but we need to increase the likelihood that a criminal will be caught. Mentally ill persons should not be forced into the community where they may injure other persons and end up in prison. Police should be allowed to devote their energies toward apprehending criminals who are doing real harm to victims. There is a need for an experimental study regarding the consequences of legal actions that would provide information necessary to determine what punishment is most likely to prevent recidivism. 1037 references.