This chapter begins with a discussion of the differences between the adult and juvenile justice systems, including the different vernacular, guiding philosophies, and procedures. We then provide an overview of risk factors for juvenile delinquency within three categories: biological (e.g., hormones, brain development, and ADHD); psychological (e.g., personality traits and the “maturity gap”); and environmental (e.g., parent-child relationship, antisocial peers, and education). Next, we discuss nine necessities required for juvenile correctional workers to understand their juvenile offenders and to meet their needs. We then review some of the treatment modalities shown by research to address juvenile delinquency, including family counseling and the use of risk and needs assessments tailored to juvenile offenders.