Context: Panel management is an innovative approach for population care that is tightly linked with primary care. This approach, which is spreading rapidly across Kaiser Permanente, represents an important shift in population-care structure and emphasis, but its potential and implications have not been previously studied.Objective: To inform the ongoing spread of panel management by providing an early understanding of its impact on patients, physicians, and staff and to identify barriers and facilitators.Design: Qualitative studies at four sites, including patient focus groups, physician and staff interviews, and direct observation.Findings: Panel management allows primary care physicians to use dedicated time to direct proactive care for their patients, uses staff support to conduct outreach, and leverages new panel-based information technology tools. Patients reported appreciating the panel management outreach, although some also reported coordination issues. Two of four study sites seemed to provide a more coordinated patient experience of care; factors common to these sites included longer maturation of their panel management programs and a more circumscribed role for outreach staff. Some physicians reported tension in the approach’s implementation: All believed that panel management improved care for their patients but many also expressed feeling that the approach added more tasks to their already busy days. Challenges yet to be fully addressed include providing program oversight to monitor for safe and reliable coordination of care and incorporation of self-management support.Conclusion: Subsequent spread of panel management should be informed by these lessons and findings from early adopters and should include continued monitoring of the impact of this rapidly developing approach on quality, patient satisfaction, primary care sustainability, and cost.