PROJECT ABSTRACT The current proposal seeks to study implementation of integrated substance use and mental health services for justice-involved young (JIY) women in Brazil. Despite a significant rise in rates of substance use disorders among JIY women (age 18-24) globally the past decade, implementation of evidence-based substance use services remains critically low in low- and middle-income countries (LMIC), and the global health field has made minimal progress in rigorously examining factors governing their implementation. Co-occurrence of substance use and psychiatric disorders among JIY women is the norm worldwide, with exposure to trauma theorized as a mechanism underlying the onset and mutual maintenance of co-occurring symptoms. In LMIC like Brazil, substance use services are delivered in isolated and minimally funded healthcare systems by providers with low capacity to address simultaneous psychiatric symptoms and exposure to trauma that may generate and maintain substance use. Contextually appropriate integration of substance use and mental health services (i.e., concurrent provision of substance use and mental health services by one or a set of providers) may be a viable means of increasing implementation of substance use services for JIY women in LMIC settings. The proposed study leverages advances in substance use services research, implementation science, juvenile justice, and global health to guide integration of Contingency Management (CM), a gold standard substance use intervention, with brief cognitive behavioral therapy (CBT) services for JIY women re- entering community from juvenile detention in Brazil. JIY women released from detention (age 18-22 years) are a high-risk population with elevated rates of substance use relapse and high rates of co-occurring psychiatric disorders and trauma exposure. Mixed-methods data will be used to explore individual- and provider-level barriers and facilitators to integration of CM/CBT services for this population. An understanding of multi-level implementation factors will inform development of a provider implementation plan in integrated CM/CBT services delivery. A mixed-method open trial will examine preliminary feasibility and acceptability of integrated services. The provider implementation plan will include trauma-informed considerations to enhance implementation of substance use services. Study findings can be used to inform best practices for delivering integrated substance use and mental health services for JIY adult populations in LMIC, as well as high-income countries where implementation of integrated interventions significantly lags. Findings may also serve as an important demonstration project in LMIC settings as they tackle the significant burden of young adult substance use. The study benefits from well-established community collaborations in Brazil, a strong mentorship team, and the F32 applicant’s prior global mental health research training to fulfill its aims.