Through a collaboration of the Health Intervention Projects for Underserved Populations (HIPUP) of the Public Health Institute (PHI) and the Lyon Martin Health Services (LMHS), Mariposa Project for transwomen of color in Alameda and San Francisco Counties aims to increase engagement in care with substance use disorders (SUD) and/or co-occurring substance use and mental disorders (COD) who are at risk for, or living with HIV and receive HIV primary care. Mariposa Project will engage with the population of high-risk transwomen of color, provide evidence-based intervention programs (EBPs) [Motivational Enhancement Intervention (MEI) and Trauma-Focused Cognitive Behavioral Therapy (TF-CBT)] to reduce substance use and HIV risk behaviors and promote health and well-being, and link clients to appropriate community-based behavioral health services, including trans-sensitive and trauma-informed SUD and COD treatment, HIV/Viral Hepatitis (VH) testing, PrEP or HIV primary care, vaccination of Hep B, and primary health care at LMHS, as well as peer-led Recovery Support Groups and Stable Housing and Employment (SHE) and other trans support programs at HIPUP. Mariposa Project will attain the following measurable objectives: 1) Conduct community- and online outreach and make a total of 6,750 contacts with high-risk transwomen of color in Alameda and San Francisco counties; 2) Screen eligibility for a total of 4,050 transwomen, and if they are screened out or decline to enroll in Mariposa Project, provide referrals for HIV/Hep testing and other health and social services at LMHS or other collaborating agencies; 3) Enroll a total of 540 eligible and consented transwomen of color into Mariposa Project (Case Management with MEI sessions and referrals/navigation to service programs), complete intake assessment and HIV and Hep testing, and provide referrals and navigation services for treatment at LMHS; 4) Enroll 54 newly diagnosed HIV positive clients or those know HIV positive status but drop out from care into HIV primary care at LMHS; 5) Enroll 270 newly diagnosed HIV negative clients or those not adhering to PrEP into PrEP program at LMHS; 6) Enroll 108 clients who are diagnosed SUD or COD into treatment programs at LMHS that are based on TF-CBT; 7) Enroll 270 clients into Recovery Support Groups (all clients are encouraged to enroll); 8) Enroll 270 clients into SHE or other trans support programs; 9) Attain 486 clients (90%) to complete Mariposa Project (5 MEI sessions and other support programs and/or SUD/COD treatment programs) and the exit assessment; 10) Retain 432 clients (80%) to complete the 6-month follow-up assessment; 11) Conduct a total of 60 monthly process evaluations; 12) Conduct a total of 5 outcome evaluations (end of each project year); 13) Disseminiate project experience and findings through 10 community forums (twice a year) and posting on the project's website and SNS (a total of 2,850 clicks). Mariposa Project is an ideal expansion and enhancement of our current services for transwomen of color who are struggling with HIV/AIDS, substance use, and mental health problems and a lack of coordination of these vital prevention and treatment services.