The objective was to evaluate the 3-year experience of a high-risk case management (HRCM) pilot program for adults with an AARP Medicare Supplement (Medigap) Insurance Plan. Participants were provided in-person visits as well as telephonic and mailed services to improve care coordination from December 1, 2008, to December 31, 2011. Included were adults who had an AARP Medigap Insurance Plan, resided in 1 of 5 pilot states, and had a Hierarchical Condition Category score>3.74, or were referred into the program. Propensity score weighting was used to adjust for case-mix differences among 2015 participants and 7626 qualified but nonparticipating individuals. Participants were in the program an average of 15.4 months. After weighting, multiple regression analyses were used to estimate differences in quality of care and health care expenditures between participants and nonparticipants. Increased duration in the program was associated with fewer hospital readmissions. Additionally, participants were significantly more likely to have recurring office visits and recommended laboratory tests. The program demonstrated $7.7 million in savings over the 3 years, resulting in a return on investment of $1.40 saved for every dollar spent on the program. Savings increased each year from 2009 to 2011 and with longer length of engagement. The majority of savings were realized by the federal Medicare program. This study focused on quality of care and savings for an HRCM program designed solely for Medicare members with Medicare Supplement coverage. This program had a favorable impact on quality of care and demonstrated savings over a 3-year period.