Ending the HIV Epidemic Scientific Working Group (EHE SWG) Project Summary/Abstract The overall objectives of the SD CFAR Scientific Working Group (SWG) program are to: 1) identify priority areas of HIV research through our strategic planning process, 2) develop research expertise and capacity in these priority areas, and 3) coordinate new collaborations across the SD CFAR network and with implementing partners (i.e., county public health departments, community partners, and local/regional clinics). We designed our SWG program to be flexible, allowing us to respond to new research priorities as they arise. We anticipate adopting 2-3 new SWG research topics during the 5-year award period. In 2019, the U.S. enacted a bold plan to End the HIV Epidemic (EHE) by implementing interventions across four key strategic pillars: 1) Diagnose; 2) Treat; 3) Prevent; and 4) Respond. In response to this historic opportunity and after a robust strategic planning process in mid-2019, the EHE Scientific Working Group (SWG) was launched in November 2019. Since its inception, the SWG has been highly productive in securing research grant support focused on the EHE pillars. These accomplishments fueled continued enthusiasm during the SD CFAR 2021 Strategic Planning Retreat to maintain the SWG’s focus on EHE as an opportunity to expand and strengthen our activities in 2022-2023. The EHE SWG convenes established and early career investigators, as well as implementing partners with diverse expertise and interest in developing better approaches to achieving EHE targets. The EHE SWG capitalizes on: 1) location within a southwestern “geographic hotspot” that includes six geographically contiguous high burden counties (5 in southern California, 1 in Nevada), and 1 nearby jurisdiction in Arizona; 2) a long history of successful community-academic partnerships; 3) outstanding clinical, epidemiology, and translational science research infrastructure; and 4) a successful partnership with the internationally-renowned implementation science experts of the UCSD Altman Clinical Translational Research Institute Dissemination and Implementation Science Center (DISC) - which led to the 2020-2023 funding of the SD CFAR Implementation Science (IS) Hub. With guidance from PAR-20-106 and input from SD CFAR members, we will address the following specific aims: 1. Expand Research: Expand partnerships with implementing partners and identify new priority areas of HIV research for future SWG research topics. 2. Engage and Network: Engage a broad range of scientific experts from the four EHE pillars to present and participate in regular EHE meetings and support SWG partnerships. 3. Educate and Train: Educate SD CFAR members on EHE goals and support the training of the next generation of scientific leaders in EHE research (and future SWG focus areas).