Since the 1970s, those working in the field of juvenile justice have sought ways to classify offenders by their likelihood of future delinquency—primarily through the use of actuarial risk assessments. As more such assessment instruments were developed and put into use, some juvenile justice practitioners and researchers began raising concerns about the classification and predictive validity of several of these risk assessments. In response to those concerns, the Office of Juvenile Justice and Delinquency Prevention funded NCCD to conduct a study of eight risk assessments in 10 jurisdictions across the United States. NCCD researchers, in consultation with an advisory board of juvenile justice researchers and developers of commercial juvenile justice risk assessment systems included in the study, compared the assessments’ predictive validity, reliability, equity, and costs.