Using data from the 2015 Current Population Survey – Annual Social and Economic Supplement, this analysis presents estimates of the characteristics of those remaining uninsured after implementation of the Affordable Care Act’s coverage provisions. The researchers also analyze the characteristics of two subpopulations that they posit are those for whom additional outreach and enrollment efforts are likely to be most successful: those eligible for Medicaid/CHIP but not enrolled and those who are both eligible for Marketplace tax credits and have incomes below 200 percent of the federal poverty level. They present potential targeted outreach strategies based on the characteristics of these groups.