Modified Project Summary/Abstract Section (Developmental Core) The mission of the UCSF-Bay Area CFAR is to promote multi-disciplinary HIV research, and the Developmental Core plays a central role. The Core is the principal vehicle CFAR uses to support investigators across the CFAR, with a particular focus on early-stage investigators (ESIs). From 2011-2021, CFAR funded 170 pilot awards for a total of $8.64M, resulting in $156M in follow-on funding from NIH, a 17-fold return on investment. These 170 awards yielded 525 resultant publications, 17 K-level awards, 15 R21s, 27 R01s and 20 other NIH awards. Of 23 supplements awarded in the last decade, totaling $3.8M, NIH funding was $82.2 million, a 21 times return on investment. Since our last renewal, the Core has mentored 87 early-stage investigators (ESIs) in its formal Mentoring Program; trained 156 researchers in our innovative “Mentoring the Mentors” program on techniques of effective mentoring (226 since the inception of the workshop in 2012); and completed a long-term evaluation of both the local mentoring program and the national Mentoring the Mentors program. During this project period, CFAR funded 72 awards (2 co-funded) in a direct costs amount of $3.1M. Going forward, the Developmental Core will advance its dedicated commitment to supporting emerging leaders in HIV research through a comprehensive set of activities centered on four specific aims: (1) to sustain and refine a comprehensive two-year mentoring program for early career HIV investigators, providing each with access to the tools needed for future success in research. This CFAR Mentoring Program pairs mentees with senior CFAR mentors, provides monthly career developmental workshops, hosts a yearly symposium with Excellence awards, provides a yearly leadership retreat, and provides specific aims reviews before each grant deadline; (2) to conduct annual “Mentoring the Mentors” workshops to train HIV researchers from CFARs around the U.S. in tools and techniques of mentoring. We have also traveled to other CFARs to provide this Mentoring the Mentors workshop and provided programs on mentoring programs for trainees in other forums; (3) to support innovative research and the development of ESIs through four different types of peer- reviewed awards; and (4) to advocate for and support investigators in navigating barriers in academia, and provide them with key career, mentoring, and professional development support. Therefore, the revised and expanded Developmental Core of the UCSF-Bay Area CFAR will continue to be at the center of driving innovation in HIV research locally, nationally, and globally.