An alarming number of adolescents regularly engage in activities that place them at risk for adverse mental and physical health consequences. In addition to risk-taking behaviors, adolescent psychopathology raises concern. Research indicates that the majority of adolescents who are severely emotionally disturbed do not receive any kind of mental health care at any point during their high school years. Responding to the need for validation of a new screening instrument designed to detect at-risk adolescents, this study examined the scope and clinical utility of the Classroom Screening scale (CLASS) of the Personality Inventory for Youth (PIY). Adolescents (n=223) attending a metropolitan Detroit high school completed a variety of self-report measures, including the newly-constructed PIY, and participated in a clinical interview. Analyses included correlational data, sensitivity, specificity, predictive values, and receiver operating characteristic (ROC) curves. The data indicate that CLASS is capable of detecting adolescents at risk for a broad range of difficulties, including psychopathology, psychosocial problems, and risk-taking behaviors. Thus, CLASS may be useful as a global screening measure for clinical or research purposes involving comparable populations. (BF)