Research indicates that many youth who come into contact with the juvenile justice system may have mental health- and substance use-related disorders. Problems related to these conditions play a continuing role in delinquency and pose risks to the welfare of youth, juvenile justice staff, and others. Identifying troubled youth is the first step in providing them with appropriate treatment. To take that first step, juvenile justice professionals need reliable screening and assessment instruments and practical guidance in their effective use. This book offers a comprehensive, user-friendly synthesis of current information on instruments that can be used to screen and assess youth for mental health- and substance use-related disorders at various stages of the juvenile justice process. The book includes profiles of over 50 instruments, guidelines for selecting instruments, and best practice recommendations for diverse settings and situations.