Galvin and Polk identify three factors which have spurred the development of parole guidelines: criticism of the rehabilitation model as a basis for parole decisionmaking and movement towards a just deserts model of punishment, the development of sophisticated statistical procedures for risk assessment, and increasing concern about disparity in parole decisionmaking. They also argue that parole guidelines should systematically relate sentence served to offense severity and other specified factors, provide for public protection through systematic use of risk assessment techniques in parole decisionmaking, and consider offenders' progress based on institutional performance. Hoffman and Beck (1974) discuss the use of the Salient Factor Score in Federal parole guidelines. A risk-by-severity matrix displays the suggested range of time to be served for each matrix cell. Validation studies indicate the Salient Factor Score retained predictive power. Other parole classification instruments discussed in the literature are the Wisconsin model and the Oregon Parole Matrix. The literature also discusses systems to predict recidivism, violence, and success on parole as well as parole services and functions. 17-item annotated bibliography.