In this dissertation, I examined the psychosocial effects of progressing through the youth criminal justice system. The studies presented here are tied together by the shared goal of promoting a welfare-based youth criminal justice system that adopts an extended responsibility of care toward justice-involved youth beyond reducing recidivism. Study 1 examined how clinician-derived diagnoses and recommendations are determined in a forensic context when youth provide information about their mental health that is consistent, or inconsistent, with information provided by their caregivers. Clinicians weighed information from youth more heavily when making internalizingspectrum diagnoses such as mood or anxiety disorders, whereas information from caregivers was more heavily weighed when making externalizing-spectrum diagnoses such as conduct disorder, and clinical recommendations. Study 2 examined changes in the mental health, self-esteem, and perceived social support, of justice-involved youth as they transitioned through the adjudication period of the youth criminal justice system process. Mental health and self-esteem were significantly different across time, with greater negative changes associated with longer adjudication times. Youth who committed sexual offences reported significantly greater negative changes in mental health and self-esteem compared to youth who committed non-sexual offences. Using a mixed-methods approach, Study 3 examined if, and how, justice-involved youth experienced stigma associated with criminal justice system involvement (offending-based stigma). Justice-involved youth experienced moderate internalized offending-based stigma, with greater internalized stigma associated with greater mental iii health symptoms, and lower self-esteem. The qualitative findings indicated justiceinvolved youth construct themselves as devalued members of society because of their offending status. Using an intersectional lens, how youth took up their offending status depended on how they also took up their race, masculinity, and class. This dissertation applied a broad inter-disciplinary lens, drawing on several fields of study, including correctional policy, criminogenic risk, developmental criminology, developmental psychopathology, forensic assessment, forensic mental health, human rights, intersectionality, legal discourse, and stigma. The conclusions presented in this dissertation build on the empirical foundation provided by these works to further demonstrate the youth criminal justice system in Canada must move away from a strict focus on reducing recidivism among justice-involved youth.