The criminal justice system is the primary institution responsible for the formal social control of criminal deviance. Those who violate the criminal law are subject to a variety of sanctions, ranging from the reprimand of a police officer to execution by hanging. Most offenders are not apprehended, and among those who are arrested many are not prosecuted nor convicted of a crime. For offenders who are found guilty, either by trial or more often by negotiated guilty plea, the sentence handed down by the court typically mandates correctional supervision, usually either some form of probation or incarceration with early release to some form of parole.

Even though probation and parole have been integral components of corrections since the nineteenth century, the differences between them are not always clear. Both are postconviction alternatives to incarceration that include supervision in the community by a probation or...