Based on national statistics, more than a third of youth involved in juvenile justice (YJJ) have a substance use disorder (SUD), with rates increasing among YJJ across justice system penetration. This finding is staggering given that the US prevalence rate of SUDs is 7% among general population adolescents. Thus, the ability to provide effective SUD treatment is pertinent for YJJ. Although evidence-based interventions (EBIs) for SUDs exist, few youth in general, and YJJ specifically, access EBIs. Moreover, there is evidence to suggest racial/ethnic disparities in access to SUD treatment within juvenile justice (JJ), such that racial/ethnic minority youth are less likely to be referred to substance use services within JJ compared to their White peers. However, it is plausible similar disparities exist throughout the SUD treatment cascade from referral to treatment completion within JJ, warranting the need for more focused research within this area. The primary goal of the proposed minority supplement is to build off of the work conducted within the parent project, Alliances to Disseminate Addiction Prevention and Treatment (ADAPT), which addresses barriers to YJJ achieving the SUD care cascade (i.e., referral to treatment, treatment initiation, and engagement), by examining whether there are racial/ethnic disparities within each point of contact within the cascade of care for YJJ. We will examine data across the department of juvenile justice and community mental health centers (CMHCs) who provide SUD treatment for YJJ within three rural Indiana counties (Bartholomew, Monroe, and Porter), and compare differences between Black and Latino/a youth and non-Hispanic White youth on five defined contact points with the SUD care cascade: screening, needs assessment and identification, referral, initiation, and utilization. We hypothesize that fewer Black and Latino/a YJJ will be screened and referred to SUD treatment, as well as initiate or utilize treatment compared to non-Hispanic White YJJ. It has also been noted by the Institute of Medicine, that many sources, including but not limited to the health care system as a whole, health care provides, and patients, contribute to racial and ethnic disparities in health care treatment. Thus, it is plausible that similar sources are relevant within JJ and CMHCs in the treatment of SUD for YJJ. Thus, the second and third aim of the proposed minority supplement will be to employ a multi-system, multi- method approach to identify barriers and strengths at both the system and individual-level. The advantage of a multi-system, multi-method approach to examining the SUD care cascade for racial/ethnic YJJ will provide an opportunity to identify potential broken links in the alliances between the JJ system and CMHCs. Moreover, given that EBIs are most effective when implemented in a culturally adapted manner that addresses the needs of youth and families, our findings will be able to inform how EBIs for SUD are impleme...