PROJECT SUMMARY/ABSTRACT NOT-DA-19-048 Adolescent females in juvenile justice settings engage in multiple health risk behaviors that place them at risk for HIV and pregnancy affected by alcohol and marijuana. Specifically, they engage in frequent sexual risk behaviors, placing them at risk of pregnancy, STIs and HIV, while also using marijuana, and alcohol. With nearly half of U.S. pregnancies being unplanned, females unaware of their pregnancy will continue to drink or use marijuana during the early and critical weeks of gestation, which places them at risk of substance-exposed pregnancy. The long-term goal of this proposed line of research is to develop efficient and opportunistic interventions that reduce the risk of substance-exposed pregnancy (SEP) and HIV/STIs for justice involved female youth. Therefore, the overall objective of this study is to test the efficacy of CHOICES-TEEN (CT) for reducing the risks of SEP and HIV/STI in young women involved in community probation or diversion programs. CT was adapted from the CHOICES preconception intervention and its shorter version, CHOICES-PLUS, which have a robust history of efficacy in reducing the risk of alcohol and tobacco-exposed pregnancy with high-risk adult women. CT utilizes Motivational Interviewing (MI), which has demonstrated significant promise with adolescents and criminal justice populations. Our recent pilot study (R03DA034099; CHOICES-TEEN; CT-P), in which we adapted CHOICES for teens and tested its feasibility with youth on community probation, produced promising results. CT was modified based on this pilot work to 1) focus on marijuana (reported by 89% in CT-P study) rather than tobacco given the low prevalence and sporadic nature of nicotine use reported by the teens; 2) add a mobile health application to increase engagement with the daily journal and; 3) incorporate a post-CT self-regulation component targeting behavioral processes of change (POC). This study will move the field vertically by elucidating important factors influencing youth health behavior change, while testing an intervention designed to reduce individual and societal costs for this high risk, underserved adolescent population. The next logical step is to conduct a rigorous RCT to assess the efficacy of this gender-responsive, tailored bundled risk reduction intervention for young, primarily minority, women involved in a community-based juvenile justice diversion or probation program. A stage II behavioral intervention efficacy trial will: 1) Primary Aim: Test the efficacy of CHOICES-TEEN (CT) on reducing the risk of substance-exposed pregnancy (SEP) and HIV/STI among high-risk female youth involved with the juvenile justice system by reducing alcohol use, increasing marijuana cessation, reducing pregnancy risk, and increasing condom use. Aim 2: Test the efficacy of CT, compared to SC, in increasing cognitive self-regulation abilities; Aim 3: Test proposed intervention mediators/mechanisms of action for CT ...