ABSTRACT Reductions in the health burden of tobacco and other substance use and of overdose mortality have not been equitably distributed. A minority of persons with substance use disorder (SUD) access treatment. To improve the equity in the delivery of evidence-based treatment of opioid-, tobacco- and other SUD, rigorous training is needed to prepare the next generation of investigators in patient-oriented addictions research (POAR). I am a general internist who has provided integrated primary care and opioid use disorder (OUD) treatment for over 16 years, co-direct fellowship programs to train general internists skills in SUD clinical care and research, and lead a research program that aims to enhance tobacco treatment outcomes and delivery among persons with co-occurring mental health and SUD. This Mid-Career Investigator Award will be used to support three overarching career goals. First, this will formalize and expand my research mentoring activity to fellows and early-career faculty focused on POAR. I will focus particularly on mentoring investigators from racial/ethnic minority groups that are underrepresented in academic medicine and NIH-funded research. Second, I will develop specific expertise in experimental and implementation science methods to enhance intervention optimization and translation of clinical research findings to real-world application. The proposed research will use a stakeholder-informed approach to develop and pilot test a flexible methadone treatment intervention. This will both inform flexible, patient-centered, equitable care delivery in OUD treatment, and provide a platform for research training for mentees in experimental and implementation science. Finally, I will develop leadership skills in academic medicine to expand the research training infrastructure to promote equity and diversity, and enhance research training in POAR. The proposed K24 application will leverage my strong existing research program, an outstanding team of advisors, and robust institutional resources in research and clinical care among persons with mental illness and SUD to support my career development and mentorship of early-career investigators.