Recently, the Oregon Health Insurance Experiment has provided uniquely powerful evidence about the impact of Medicaid coverage on uninsured adults.12 13 14 The evidence is compelling because the study is a randomized controlled trial (RCT), the gold standard in research design. Taking advantage of a lottery held in Oregon in 2008 to allocate a limited number of new Medicaid “slots” for low-income, uninsured nonelderly adults, a team of researchers gathered data on access, utilization, and clinical health measures for both the adults who gained Medicaid through the lottery and the adults who did not. Two rounds of findings have been published in the New England Journal of Medicine, which can be summarized, in part, as follows: - kff.org