This k24 is an application for mentoring junior investigators in behavioral interventions related to HIV treatment and prevention, specifically focusing on associated psychosocial syndemics relevant to HIV prevention and care. Mental health problems, including substance abuse, are of the most frequent comorbidities to HIV and are consistently identified as barriers to adherence, engagement in care, and reductions in risk behavior. Typically these problems co-occur as syndemics (co-occurring psychosocial problems that interact with each other and with HIV risk). Candidate. The candidate has over 10 years of NIH-funded support addressing mental health, substance abuse, and psychosocial comorbidities in the context of interventions for HIV/AIDS. This includes interventions for depression and adherence in HIV, domestic and international primary and secondary prevention studies, and mentee projects addressing various syndemic indicators and HIV prevention in men who have sex with men (MSM). The candidate also has a strong and consistent successful mentoring history, including over 30 fellows and junior faculty, resulting in >60 publications with mentees as first author. Mentoring Plan/Environment. The candidate is Director of Behavioral Medicine in the Department of Psychiatry at Massachusetts General Hospital (MGH) / Harvard Medical School (HMS), Co-Director of the Harvard University Behavioral Sciences Program for the CFAR, and an affiliated faculty at Fenway Health. In these roles, the candidate has been receiving increasing and multiple requests to mentor junior level clinical researchers across disciplines. He has access to psychology / behavioral medicine mentees generally from the MGH clinical psychology training program, access to local physician and public health mentees through the Harvard University CFAR, which stems all of the Harvard Hospitals, additional local hospitals (e.g. Shattuck Hospital) the Harvard School of Public Health, and Harvard programs. He also is receiving increasing requests to mentor national and international colleagues in behavioral science methods through the CFAR and NIAID CTU networks and other sources. These emerging and established scientist mentees typically require mentoring in behavioral intervention development and testing, including incorporating behavioral science into biomedical or epidemiological science projects. The current project will allow him to accommodate and grow these requests through protected time for mentoring. Research Plan. The candidate's depression/adherence studies in HIV, although successful in treating depression and improving adherence, to date have found exceptionally high levels of comorbidity in patients with HIV and depression. This has raised the need to address other syndemics (e.g. substance abuse, PTSD, other anxiety disorders) in addition to depression in the context of care. As a platform for mentee involvement in research, the candidate will leverage his existing R01 on treating depression in HIV, to begin to learn how to best treat the most frequent syndemics with HIV, in the context of improving health-related behavior change.