PROJECT SUMMARY The proposed project quantitatively and qualitatively investigates and disseminates the mechanisms underlying potential racial/ethnic and sex differences in risk for substance use disorder (SUD) and disparities in SUD treatment services among justice-involved adolescents (JIA). JIA are a critically underserved population who are especially vulnerable to SUD. Certain ethnic groups and females in the juvenile justice system are predisposed to harsher consequences of substance misuse and are more prone to suffer from undiagnosed SUDs. The cascade of care is a novel framework for investigating unmet treatment needs. The stress process model hypothesizes that disparities occur due to unequal distribution of stressors and resources, offering a major pathway linking race/ethnicity and sex to disparities at the cascade checkpoints. The study will synergize transdisciplinary theory and methodology through integrating a) a sociological theory of health disparities—the stress process model, b) a novel framework for measuring unmet treatment needs–the cascade of care, c) advanced quantitative methods –mediation analysis in structural equation modeling, and d) innovatory qualitative approaches–hybrid thematic analysis with cutting-edge technologies. The specific research aims are to 1) investigate if stress and resources mediate racial/ethnic and sex differences in substance misuse (SM) patterns; 2) test if stress and resources mediate ethnic and sex disparities in referral to SUD screening, diagnosis with SUD, treatment initiation and treatment completion; and 3) qualitatively explore how stress and resources relate to ethnic and sex disparities in SUD services and post-release outcomes. The study employs mediation analysis in structural equation modeling to analyze a statewide longitudinal database of 100,000 JIA from the third largest juvenile justice population in the United States. To uncover deeper insights into the statistical findings, the project conducts and analyzes in-depth interviews and surveys among 60 individuals who experienced SM and incarceration as minors. Hybrid thematic analysis will be employed to fuse the quantitative and qualitative data. These aims serve to fulfil NIDA’s mission to advance science on the etiology of SM, improve SUD prevention and treatment, and advance research on minorities, females, and other populations facing disproportionate consequences of misuse. To complete the research aims, an extensive training plan directed by a network of expert mentors who are leaders in the field will be executed. The training aims are to develop expertise in SUD services delivery in criminal justice systems; mediation analysis in SEM, psychometrics, censored data, and longitudinal design; interviewing methods in health research and analysis with the ATLAS.ti software; stress instrumentation; and implementation and translational science. These training and subsequent research activities are a major step towards developi...