The phenomenon of crime and its causation should be understood so correctional practitioners can deal more effectively with offenders under their supervision. A theory is an intellectual scaffold around which is constructed an edifice of useful knowledge. Five theories of criminality are anomie, differential association, control, psychopathy/love deprivation, and lifestyle theory/biosocial factors. Anomie includes cultural values, norms, social structure, and lack of legitimate opportunities. Differential association includes gangs, peer pressure to conform to subcultural values and beliefs opposed to lawful behavior. Control theory is unique personal experiences leading to lack of attachment and to criminal beliefs. Psychopathy is thinking and acting patterns of criminals. Biosocial factors include inherited and acquired characteristics, possibly resulting from severe love deprivation in childhood. Correctional theory is the ideology or philosophy of punishment and justice that is in vogue within the criminal justice system. Correctional workers practices and decisions relating to offenders is heavily influenced by the prevailing correctional philosophy. The two guiding philosophies throughout the present century are the retributive and the rehabilitative. Partly because these philosophies have been deemed ineffectual, the new model has become restorative justice. The difference between restorative justice and previous models is its belief in the effectiveness of active community participation in corrections. Restorative justice “personalizes” crime by defining it as a harmful act committed by one person against another rather than an act committed against “the state.” It also holds offenders fully accountable for their actions by applying appropriate punishment and requires offenders to accept responsibility for taking action to repair the harm done. Specific programs include the balanced approach, so named because it gives equal weight to three important objectives: community protection, offender accountability, and offender competency. It was originally developed as a model for juvenile probation, but it also can be applied to probation work with adults. The system is shifting from focus on offenders to a dual focus on offenders and victims. 13 references, 1 figure