In May 2011, the American College of Physicians (ACP), a membership organization of physicians who specialize in internal medicine, established a probability-based, invitation-only research panel to learn more about the needs and interests of members. After three waves of invitations, 952 ACP members had joined. In summer 2012, a process of “panel hygiene” was initiated with the goal of clearing the panel of non-participants and replacing them with a new round of invitees. Analysis revealed that 30% of panelists had completed no surveys or only one since joining. Brief surveys were sent to these panelists asking if they wished to remain on the panel. Panelists who did not respond to this survey and those who responded “no” were dropped from the panel. Beginning in October 2012, invitations to join the panel were sent to a new sample of ACP members. This five-minute presentation is based on an analysis of one year of panel participation data and highlights findings regarding participation rates and panelist retention. Over the course of one year, seventeen surveys were sent to panelists. Participation rates were influenced less by demographic factors, such as age, gender, or career stage, than by how soon after joining the panel panelists received their first survey. Forty percent of panelists who received their first survey over two weeks after joining completed no surveys in a year, compared to fourteen percent of those who received their first survey within ten days. The findings underscore the importance of minimizing the time between when a panelist joins a panel and when s/he receives the first survey. Additionally, analysis reveals that as a mechanism for engaging panelists, “quick polls” and other low incentive opportunities are no replacement for surveys offering higher value rewards. Recommendations based on the findings are discussed.