This study examines the effectiveness of Washington State’s Medicaid Buy-In (MBI) program—Healthcare for Workers With Disabilities (HWD)—which gives workers with disabilities who earn too much for conventional Medicaid the opportunity to purchase full Medicaid coverage by paying a monthly premium based on a sliding income scale. The authors compare HWD enrollees who recently had conventional Medicaid coverage to a statistically matched group of individuals who had conventional Medicaid coverage in recent history and at baseline. Their findings suggest that MBI in Washington State is encouraging work, increasing earnings, and decreasing reliance on food stamps while providing medical coverage to a vulnerable population for whom continuous health insurance is particularly important.