One approach to classification of criminal cases suggests that controls are best allocated to those at risk and services to those in need. The Level of Supervision Inventory (LSI), a 58-item risk/needs checklist developed in Ontario Probation and Parole, was completed on the basis of reviews of official records and interviews with subjects and collaterals for adult probationers (N=853) and prisoners (N=227) serving sentences of 90 days to 2 years. Results showed that the areas of risk and need combined to form a scale of internal consistency. An underlying variable corresponding to a propensity for rule violations was suggested. Total LSI scores were most strongly associated with measures of generalized rule violations, emotional/personal disturbance, and skill deficits. In both prison and probation samples, intake LSI scores were positively correlated with indices of official levels of supervision. Further investigation suggested that the predictive validity of risk/needs assessments may increase dramatically upon reassessment. The same pattern of predictive validity was found across correctional settings; samples differing in age, gender, and criminal history; measures of deviance; and over variations in the frequency and seriousness of new charges. Results support the principle of allocating intensive services according to risk and need. (The LSI is appended.) (NRB)