Since its passage in 2010, the Affordable Care Act (ACA) has made tremendous progress in improving access to health insurance and health care for millions of Americans. Approximately 14.1 million previously uninsured Americans gained health insurance between the beginning of open enrollment in October 2013 and March 4, 2015. In fact, by that date, the share of Americans who were uninsured had dropped to 13.2 percent, compared to 20.3 percent at the end of 2013—the largest decrease in the number of uninsured since 1965. Some of the greatest declines in uninsured rates were for lower- and middle-income consumers, including those eligible for tax credits to help pay their premiums for plans in the health insurance marketplaces. Data from the Department of Health and Human Services also show that more than 11 million people selected plans through the marketplaces, and more than 85 percent of these consumers qualified for premium tax credits.