This Visualizing Health Policy provides a snapshot of the role of the Medicare Advantage plans, an alternative to traditional Medicare, including information about the proportion of Medicare beneficiaries who are enrolled in Medicare Advantage, geographic differences in Medicare Advantage penetration, the trend of increasing enrollment in Medicare Advantage plans, and the concentration of enrollment within a small number of firms and affiliates. It also shows the extent to which Medicare has been paying more for beneficiaries in Medicare Advantage plans than for those in traditional Medicare, although that payment differential is projected to decline.