<p><strong>Objectives:</strong> Compared to youth without justice-involvement, justice-involved youth are more likely to experience substance use disorders. Yet, few justice-involved youth receive appropriate, evidence-based treatment for substance use disorders. Although there are numerous barriers to the accessibility of appropriate treatment, research also suggests that it is difficult to engage justice-involved youth in treatment even when it is available and accessible. It is possible that substance use disorder stigma, or negative attitudes towards youth with substance use disorders, may contribute to low treatment accessibility, and make it more difficult for justice-involved youth to engage with available treatment. Few researchers have examined substance use disorder stigma among this population. The purpose of this study was to 1) explore the nature of substance use disorder stigma among justice-involved youth, at multiple ecological levels and 2) examine the role of substance use disorder stigma in limiting the accessibility of and engagement in treatment and justice-involved youth’s engagement in treatment. </p> <p><strong>Methods:</strong> Participants (n = 44 youth-guardian dyads) were referred to the study by juvenile probation departments in two Indiana counties. In addition, 66 system personnel participants who work with justice-involved youth with substance use disorders were recruited from community mental health centers and juvenile probation departments in rural and suburban Indiana counties. All participants completed survey measures of substance use disorder stigma and familiarity with substance use; youth-guardian dyads also provided information about the youth’s substance use history and treatment utilization. A subset of participants (n = 9 youth, 11 guardians, 12 system personnel) completed qualitative interviews, providing perspectives on substance use disorder stigma and the role of stigma in discouraging treatment. Using analysis of covariance, multiple regression analyses, and qualitative grounded theory analysis, I explored the nature of stigma toward justice-involved youth with substance use disorders and examined the impact of stigma on treatment accessibility and engagement. </p> <p><strong>Results:</strong> For aim 1, as hypothesized, public stigma (assessed by survey data) varied significantly according to participant role and specific substance, with guardians endorsing greater stigma than system personnel. All participants expressed greater negative emotions towards youth with opioid use disorder compared to marijuana use disorder. Interview data revealed particularly nuanced attitudes about marijuana use. Contrary to expectations, youth reported little self-stigma. Both youth and guardians described limited knowledge of problematic substance use. For aim 2, interview data suggests that youth and guardians may identify more stigma associated with seeking treatment for problematic substance use than with using substances. All participants reported that perceived stigma has improved in recent years, and that youth feel more comfortable discussing their substance use. However, guardians identified family attitudes about behavioral health treatment as negatively impacting engagement among youth. In addition, system personnel reported that stigma continues to limit the accessibility of youth SUD treatment.  </p> <p><strong>Discussion:</strong> Youth endorsed lower than expected levels of self-stigma with no difference by primary substance type; this may have been affected by youth’s limited understanding of problematic substance use and lower than expected heterogeneity in substance use type among participants. Consistent with prior research, self-stigma was directly related to the severity of mental health symptoms. The high prevalence of public stigma among guardians of JIY with SUDs suggests that parents and guardians would benefit from interventions to better support their caregiving experiences. All participants identified complex attitudes about marijuana use, suggesting that the increasing public acceptability and endorsement of marijuana as a helpful substance may complicate treatment seeking when use becomes problematic. Although youth did not conceptualize self-stigma as a barrier to treatment, given that the primary substance used in this study was marijuana, these results may be complicated by changing societal attitudes about marijuana in particular. Qualitative perspectives from guardians and system personnel suggest that substance use disorder stigma may limit both the accessibility of treatment and youth’s likelihood to engage with treatment; this may depend on type of substance used. Particularly for the participants in this study, extremely limited treatment accessibility posed the largest barrier to evidence-based substance use disorder treatment for adolescents, making it difficult to accurately assess the role of stigma in actual treatment use. Finally, findings suggest that measuring substance use disorder stigma may be dependent on participants’ ability to accurately identify problematic substance use. It may also be important to refine both qualitative and quantitative measurement of stigma specifically with adolescents. Limitations and suggestions for future research are discussed.</p>