The Health Maintenance Organization Research Network (HMORN), a consortium of 19 health care delivery systems with integrated research centers, held their 18th annual conference in Seattle, Washington from April 29 to May 2, 2012. Group Health Research Institute hosted the conference, "Learning health care systems: Leading through research". The 2012 theme was chosen to reflect the critical role of collaboration among researchers, clinicians and health systems to improve health care nationally. Over 500 researchers and health care professionals participated in this conference. Representatives from the NCI, NHLBI, NIMH, and PCORI met with researchers to advance the quality and breadth of public domain research in HMOs. In this article we summarize information about the HMORN and its 18th annual conference.