Changes in insurance coverage over time, or "churning," may have adverse consequences, but there has been little evidence on churning since implementation of the major coverage expansions in the Affordable Care Act (ACA) in 2014. We explored the frequency and implications of churning through surveying 3,011 low-income adults in Kentucky, which used a traditional expansion of Medicaid; Arkansas, which chose a "private option" expansion that enrolled beneficiaries in private Marketplace plans; and Texas, which opted not to expand. We also compared 2015 churning rates in these states to survey data from 2013, before the coverage expansions. Nearly 25 percent of respondents in 2015 changed coverage during the previous twelve months-a rate lower than some previous predictions. We did not find significantly different churning rates in the three states over time. Common causes of churning were job-related changes and loss of eligibility for Medicaid or Marketplace subsidies. Churning was associated with disruptions in physician care and medication adherence, increased emergency department use, and worsening self-reported quality of care and health status. Even churning without gaps in coverage had negative effects. Churning remains a challenge for many Americans, and policies are needed to reduce its frequency and mitigate its negative impacts.