This survey shows that the share of 50- to 64-year-olds without health insurance fell between December 2013 and March 2014. In states that expanded their Medicaid programs, a greater share of previously uninsured adults gained coverage, particularly among groups that have traditionally faced barriers to obtaining it. The survey also found that the newly insured differed in key ways from those who reported being insured for all of the past 12 months. On average, more were low income, and more reported that they had had trouble paying medical bills. This paper is part of a series that looks at the experience of 50- to 64-year-olds during the first open enrollment period of the Affordable Care Act (ACA).