This study assessed the effectiveness of the Youth Level of Service/Case Management Inventory (YLS/CMI or Y-LSI). The Y-LSI is an instrument for classifying juvenile offender risk of recidivism and for identifying areas of treatment need that, if addressed, will result in a reduced risk of recidivism. Three juvenile correction agencies in Ohio that used the Y-LSI for case classification were the settings for this study. Data in Part 1 were collected on 1,679 youths received in the three correctional settings between July 1, 1998, and June 30, 1999. Youths' files were reviewed to complete the data collection instruments. These files contained demographic and background information, Y-LSI assessments, and information relating to treatment and service referrals, completion of programming, and supervision outcome. One year after the initial Y-LSI assessments, reassessment data were collected on youths. Reassessments were completed on youth at the time of program completion or one year after the initial assessment. Supervision outcome data were collected two years after the initial data collection. Data in Part 2 were collected in 2001 through a survey of 196 agency staff members on their reactions to the use of the Y-LSI as a classification instrument.