New estimates of gaps and transitions in health insurance.

Changes in individual or family circumstances cause many Americans to experience gaps and transitions in public and private health insurance. Using data from the 2004-2007 Survey of Income and Program Participation, this article updates earlier analyses of insurance gaps and transitions. Eighty-nine million people (one third of nonelderly Americans) were uninsured for at least 1 month during those 4 years. Approximately 23 million lost insurance more than once. The analyses call attention to the continuing instability and insecurity of health insurance, can inform implementation of national reforms, and establish a recent baseline that will be helpful in evaluating the reforms' effects on coverage stability.