This paper presents evidence of the dynamics of health insurance coverage between 2008 and 2014 among early retirees, defined as individuals ages 55 to 64 who are not in the labor force. We focus on three questions. First, how did insurance coverage change among early retirees in 2014, when the new ACA options became available, compared with trends in coverage from 2008 to 2013? Second, are there differences between states that did and did not implement the ACA’s Medicaid expansion in January 2014? Third, how did the income gradient in insurance coverage for early retirees change in 2014, both overall and in states with or without Medicaid expansion? We find that between 2013 and 2014, the fraction of early retirees without health insurance declined significantly from 14.7 percent to 11.2 percent, reversing a trend toward increasing uninsurance in recent years. This change was driven by increases in both Medicaid and private non-group coverage. Gains in coverage were larger in states that implemented the Affordable Care Act’s Medicaid expansion in January 2014 than in states that did not. The gains in coverage disproportionately benefited low-income early retirees, and therefore reduced the gradient in coverage with respect to income. There is no evidence of an acceleration of the decline in employer-sponsored coverage for early retirees, either overall or in states that expanded Medicaid. These results suggest that the major coverage provisions of the ACA have increased coverage among early retirees, with particularly large gains among those with very low income in states that expanded Medicaid.