On October 11, AcademyHealth and the Kaiser Permanente (KP) Institute for Health Policy co-hosted a forum at the Kaiser Permanente Center for Total Health titled “Practical Applications, Challenges, and Opportunities: How Registries Can Help Support a Learning Health Care System.” Participants reflected on specific examples of how patient registries have been leveraged thus far, and considered how such efforts might expand, evolve, or align with other data infrastructure initiatives in support of a learning health care system. The group of more than 50 included representatives from national and international registries, academic and research institutions, policy and other non-governmental organizations, government agencies, health care systems, and life sciences and technology companies. AcademyHealth’s President and CEO Lisa Simpson kicked off the forum by emphasizing the relevance of the registry initiatives to AcademyHealth’s mission of improving health and health care by generating new knowledge and moving that knowledge into action. Dr. Cliff Goodman of The Lewin Group facilitated the day’s panels and discussions. Introductory remarks from Tad Funahashi of Kaiser Permanente, Jean Slutsky of AHRQ, and Bradford Gray of the Urban Institute offered examples for how registries can facilitate comparative effectiveness research and quality improvement to increase the safety, quality, and efficiency of care. The speakers described federal initiatives to support registry development, including AHRQ’s efforts to create an online Registry of Patient Registries. Panelists engaged in discussions about the changing nature and variable definitions of registries, as well as lessons we can learn from European registry models. In the subsequent panels, speakers described some of the challenges encountered and keys to success for their registry initiatives, as well as described a full range of registry uses—from the tracking and comparison of patient outcomes, to the creation of clinical decision support tools, to development of evidence-based clinical guidelines. Based on these presentations and subsequent discussion, the group identified a list of priority areas for current and future registry initiatives, stressing the need for improved data linkages—especially with electronic health records, patient-reported measures, and claims data—and standardized outcome measures. Participants noted that greater linkage would facilitate more seamless data collection at the point of care, and would support the broader goal of leveraging registries to improve healthcare without overburdening the delivery system. After hearing so many promising examples of how registries have been used to reduce unnecessary expenditures and improve outcomes, participants wondered: if registries are so great, why aren’t there more? Several noted the need to better demonstrate the value of registries in order to promote sustainability and increase buy-in among both providers and potential funders. The presentations and discussions demonstrated the potential of registries to support a learning health care system, and yielded multiple recommendations on areas for further exploration. AcademyHealth is working with Kaiser Permanente and others to synthesize and organize these recommendations, and is developing a meeting proceedings document that will be available later this year. Select presentation slides from the discussion are here. We welcome your feedback and suggestions, so please join the dialogue.