[en] In response to public concern about the cleanup of the Three Mile Island, Unit 2 (TMI-2) facility after an accident on March 28, 1979 involving a loss of reactor coolant and subsequent damage to the reactor fuel, twelve citizens were asked to serve on an independent Advisory Panel to consult with the Nuclear Regulatory Commission (NRC) on the decontamination and cleanup of the facility. The panel met 78 times over a period of thirteen years, holding public meetings in the vicinity of TMI-2 and meeting regularly with NRC Commissioners in Washington, DC. This report describes the results of a project designed to identify and describe the lessons learned from the Advisory Panel and place those lessons in the context of what we generally know about citizen advisory groups. A summary of the empirical literature on citizen advisory panels is followed by a brief history of the TMI-2 Advisory Panel. The body of the report contains the analysis of the lessons learned, preliminary conclusions about the effectiveness of the Panel, and implications for the NRC in the use of advisory panels. Data for the report include meeting transcripts and interviews with past and present Panel participants