The major insurance coverage expansion provisions of the Affordable Care Act—the Health Insurance Marketplace and Medicaid expansion—went into effect in January 2014. At that time, individuals in all 50 states were able to purchase health plans during two open enrollment periods, with subsidies for those with incomes between 100% and 400% of the federal poverty level. Individuals with incomes below 139% of the federal poverty level were able to enroll in Medicaid in the 31 states that opted to expand Medicaid. This issue brief focuses on the changes in health insurance coverage among Texans ages 18-64 as of March 2015, following the ACA’s second open enrollment period. Because Texas has had the highest percentage of uninsured residents among the 50 states for many years, the coverage provisions of the ACA were expected to play a significant role in providing coverage to the more than 4 million adults ages 18-64 who previously lacked health insurance. Based on the HRMS-Texas March 2015 survey, we find that the ACA has had a substantial positive impact on the rate of health insurance coverage among Texans. The rate of uninsured Texans ages 18-64 dropped by nearly one-third, from 24.6% in September 2013 to 16.9% in March 2015. The drop is almost entirely attributable to newly insured individuals who purchased their own plans. The reduction in the rate of uninsured individuals occurred across all age groups, including younger adults. Despite this progress, Texas remains the state with the highest percentage of uninsured residents and, for the first time, Texas now has the largest number of uninsured residents. The percent of uninsured Texans with incomes above 138% of the federal poverty level dropped by 44.5% while those with the lowest income only dropped by 19.7%. As of March 2015, the lowest income Texans are almost four times more likely to be uninsured than higher income individuals. This coverage gap has grown since 2013 because the Marketplace enabled the higher income group to purchase health insurance with subsidies not available to lower income Texans. Unless Texas participates in an expanded Medicaid program or develops some other mechanism for covering the lowest income Texans, this is not likely to change.