This book provides a discussion ofadvances in our understanding of the juvenile offender. These derive from psychological and criminological theoryand researchonthe phenomenonofyouth crime and from efforts on the part of social science researchers and practitioners to develop and evaluate new approaches to prevention and treatment. The theoretical and empirical advances relate, first, to analyses of the nature and extent ofyouth crime. This is reflected, for example, in various descriptive and classification systems developed for characterizingjuvenile offenders. Significant advances are also being made in understanding the risk factors associated with youthful criminal activity, as well as the processes linking the risk factors with antisocial behaviors. This understanding is based on theory and research relatingto the correlates andcauses ofdelinquency. The advances in our understanding of the nature, correlates, and causes of juvenile crime are accompanied by progress in analyzing the treatment ofyouth in juvenile justice systems and in developing and evaluating alternative approaches to treatment. These efforts include research on decision-making within juvenile justice systems and the development of screening and assessment tools. This also includes efforts to develop and evaluate effective prevention and treatment programs for use with youths involved in criminal activity and those at risk for this activity.