Between 2013 and 2016, children’s uninsurance fell, their Medicaid/CHIP participation rate rose, and the number of children eligible for Medicaid/CHIP but uninsured declined, according to American Community Survey data. But these gains stalled in 2017 and 2018, as children’s uninsurance rose and program participation fell relative to their 2016 levels. In 2018, consistent with prior years, children’s uninsurance and Medicaid/CHIP participation rates varied across states, and long-standing disparities in coverage and participation across subgroups continued. Also like in previous years, more than half of uninsured children appeared to be eligible for Medicaid/CHIP but not enrolled. Further, just over half of all Medicaid/CHIP-eligible but uninsured children in 2017–18 lived in just seven large states (Arizona, California, Florida, Georgia, New York, Pennsylvania, and Texas).