Modified Project Summary/Abstract Section (former Housing SWG) The HIV epidemic is inextricably linked with factors disproportionately common in low-income populations. Each of these factors significantly increases the risk of HIV infection, creates barriers to testing and health care, and makes negative health outcomes much more likely. The issue at the center of it all is homelessness, which magnifies the likelihood of every other risk factor. Homelessness and unstable housing (HUH) have been recognized as major barriers to reducing HIV incidence and improving HIV viral suppression for over two decades and continue to impede Ending the HIV Epidemic goals. As the housing crisis worsens in the San Francisco Bay Area and across the country, new approaches to health care delivery and research aimed at improving strategies to address differences in HIV outcomes by housing status are critically needed. We therefore formed a new Housing Scientific Working Group (SWG), which will serve as a hub for individuals across the San Francisco Bay Area researching ways to improve HIV care engagement, treatment and prevention outcomes among people experiencing HUH. While there is a wealth of San Francisco Bay Area expertise in areas critical to, overlapping and adjacent to those influencing health outcomes in the context of HIV and housing, there is currently no forum for cross-disciplinary pollination and collaboration. Our proposed SWG in the UCSF Bay Area CFAR will provide an environment and platform that intentionally and regularly brings together researchers, local stakeholders, implementers, and policymakers to explore synergies and foster collaboration. This new Scientific Working Group on Housing and HIV will create opportunities to share ideas across academic disciplines, as well as between academia, the community, policy makers, and agencies delivering services. We will provide forums, symposia and workshops to comprehensively evaluate the existing evidence on how to improve HIV prevention and treatment outcomes among people experiencing marginal housing, and how this research might be implemented in novel ways; identify gaps in the existing knowledge base; develop new study ideas and new approaches to research; and disseminate work in the area of HUH and HIV. We will work closely with other Cores in the CFAR, including the Bio-Behavioral and Developmental Cores, and with the Intersectionality Scientific Working Group on initiatives to improve the health of those with HIV or at risk of HIV and marginal housing. This novel SWG will rally expertise across UCSF and our affiliates, including the San Francisco Department of Public Health, to work on End the HIV Epidemic goals. This Scientific Working Group has now been folded into the new Implementation Science Scientific Working Group for the upcoming project year.