Prediction is probably the most commonly used basis on which corrections officials make decisions about offenders. Prediction can be an informal or formal process. The research literature shows that the accuracy of predictions of rare behaviors such as committing a violent crime is limited. However, the understanding of ways to use statistical methods in making predictions has greatly improved in recent years, thereby improving the general ability to predict crime by classifying offenders into risk categories. The use of risk assessments has led to the use of risk management programs in corrections operations and decisionmaking. However, many precautions are needed in designing and implementing a prediction-based approach to corrections decisionmaking. Description of the use of prediction methodology in Marion County, Oreg.; figures; tables; and 79 references.