|It is important to better understand those who perpetrate sexually; however, much of the available research has been conducted with adult sex offenders. Since research has found that these adults frequently report perpetrating sexual abuse for the first time during childhood/adolescence, this study examines adolescents who have committed a sexual offense. Findings have shown that adolescents who sexually offend are most often insecurely attached to caregivers, have difficulty regulating their emotions, and display numerous internalizing and externalizing behavior problems (in addition to sexual offending). Research has shown that attachment insecurity is highly related to internalizing/externalizing behaviors and poor affect regulation skills. However, no studies have examined the relationships among attachment, affect regulation, and internalizing/externalizing behaviors in the population of adolescents who sexually offend. The purpose of this study is to identify how affect regulation ability might mediate or possibly moderate the relationship between attachment and internalizing/externalizing behaviors in this population. Sixty-two incarcerated adolescents completed self-report questionnaires regarding demographic information, internalizing/externalizing behavior problems, attachment, and affect regulation. Path analysis was the chosen method of analysis. In addition, mediation and moderation hypotheses were tested. This study found that attachment was related to internalizing and externalizing behaviors, as well as, emotion regulation. Maladaptive affect regulation appeared to have a stronger influence on problem behaviors than adaptive affect regulation in this study. Affect regulation was not found to moderate the relationship between attachment and internalizing and/or externalizing behaviors. Importantly, this study was the first to test and find that affect regulation ability mediated the relationship between attachment and externalizing behavior. The findings from this study might help professionals identify more successful therapeutic interventions for these adolescents and prevent later sexual offending and further negative, individual or societal outcomes.