Abstract - UCSF E-STaR Research Education Core Learning health systems (LHS) are critical to reducing lag time between generation of new evidence and its implementation in clinical practice; it is critical for improving patient outcomes, enhancing workforce capacity, and achieving health equity. UCSF and its partnering health care systems, UCSF Health, San Francisco Health Network, a safety-net integrated healthcare system that serves uninsured and publicly insured populations in San Francisco, and the San Francisco Veterans' Affairs Medical Center, are committed to continuing the journey as LHS. UCSF's strong foundation as an AHRQ K12 learning health system program (NIHK12HS026383) created durable relationships among operational leaders at each health care delivery systems, but unrealized opportunities remain. The proposed Research Education Core (REC) will train an even wider range of participants than those eligible for a career development award. The cohort will include Trainee- Scholars, e.g., clinical fellows or residents in their research years who wish to incorporate LHS work into their future careers, and later-stage Faculty-Scholars who are positioned to conduct LHS-embedded research with LHS-focused training and experience. The REC will integrate UCSF's proven LHS research career development program offerings with newly developed LHS-specific training infrastructure, to achieve the following Specific Aims: Aim 1. To create an integrated, modular, learning health system training pathway. A didactic and experiential curriculum with 1- and 2-year options will integrate existing training opportunities with newly developed content across the institution for 7 E-STaR Scholars in Year 1. Courses and seminars will be mapped onto LHS competencies to create a training pathway. New training developed by the E-STaR Center faculty include an Engagement Science seminar series, LHS Workshop, and LHS Grand Rounds; Aim 2. To support embedded research projects relevant to PCORI/ AHRQ priorities and co- produced by E-STaR Stakeholders and Scholars. The new interactive and didactic content to teach LHS competencies will include a weekly small-group, interactive works-in-progress seminar in which Scholars will present embedded research and receive feedback from peers and faculty. Projects will employ PCORI methodology standards with relevance to both health system improvement and external generalizability through Scholar and faculty discussion of specific Scholar works-in-progress; Aim 3. To foster learning health systems research mentorship and career development. Scholars will be integrated into UCSF's matured mentoring and career development programs tailored to their career stage, and receive focused mentoring from LHS leaders, research mentors and health system leaders. Expected Outcomes: UCSF's E- STaR training program will develop a skilled and diverse LHS workforce and durably support evolving LHS activities at UCSF and partnering health systems.