Adverse childhood experiences have been linked to dysfunctional attachment, increased likelihood of criminal behavior, and mentalization deficits. Mentalization, also known as reflective functioning, is core aspect of social functioning that involved the capacity to “interpret both the self and others in terms of internal mental states such as feelings, wishes, goals, desires, and attitudes.” This study looked at adverse childhood experiences, attachment, and mentalization in 93 registered sex offenders attending court-ordered outpatient treatment. This study revealed that sex offenders endorse significantly more adverse childhood experiences compared to the general population. It also showed that sex offenders exhibit lower attachmentrelated anxiety and attachment-related avoidance, indicating they perceive themselves as having less anxious and avoidant attachment. However, this finding may be due to their difficulty with perspective taking. The findings also revealed that sex offenders have significant deficits in mentalization and lower perspective taking abilities compared to the general population. This study explores the advantages of providing trauma-informed care to sex offenders using mentalization-based treatment