Project Summary/Abstract Compared to youth who are not involved with the justice system, justice-involved youth are more likely to be diagnosed with substance use disorders (SUDs) and less likely to access or fully engage in treatment. One potential contributor to low treatment engagement is SUD stigma. There is compelling evidence that stigma significantly detracts from the ability to access and subsequently engage in care. Although there is little extant research on SUD stigma, preliminary data suggests that SUDs are associated with different stereotypes compared to other behavioral health diagnoses and may be associated with more severe stigma. Little is known about the prevalence and potential consequences of SUD stigma among justice-involved youth or SUD stigma within the justice system. Yet given the negative consequences of mental illness self-stigma for treatment engagement, we postulate that youth with higher SUD self-stigma will be less likely to fully engage in treatment. We hypothesize that juvenile justice and community mental health staff members will report greater public stigma towards justice-involved youth with SUDs, that public stigma towards adolescents with SUDs will vary according to substance type, and that staff will describe barriers to SUD treatment indicative of structural stigma. In order to test these hypotheses, we will first deploy recently validated measures of SUD stigma to examine the nature and correlates of public and self-SUD stigma among justice-involved youth, their parents, and staff stakeholders in the juvenile justice and community mental health systems (aim 1). We will then conduct a series of qualitative interviews as well as collect data on treatment utilization to explore the impact of SUD stigma on youth’s ability to access and engage in treatment (aim 2). The proposed mixed-methods study is highly innovative and represents a crucial step in combating SUD stigma among justice-involved youth. This project includes a strong training plan and mentoring team that will help the candidate develop the skills necessary to be an independent investigator. Ultimately, this research and training will help the candidate launch a research career to develop interventions to decrease SUD stigma within the target population and thereby improve engagement in SUD treatment.