The authors analyze trends in health insurance coverage in the United States from 1989 through 1997, using cross-sectional surveys by the U.S. Census Bureau (Current Population Survey) of 160,000 persons representative of the non-institutionalized population. Between 1989 and 1997, the number of people without health insurance increased by 10.1 million to 43.4 million. From 1989 to 1993, the proportion covered by Medicaid increased by 3.6 percentage points while the proportion covered by private insurance declined by 4.2 percentage points. Since then, private coverage rates have stabilized and Medicaid coverage has decreased. Consequently, the number and percent uninsured continues to rise. Young adults age 18-39 had the largest increase in the proportion uninsured, and rates among children have also risen steeply since 1992. While blacks had the largest increase in the percent uninsured, Hispanics accounted for 35.6 percent of the increase in the number uninsured. Low-income families constituted over half of the increase in the number uninsured, but since 1993 the middle income group had the largest increase in the percent uninsured. Northeastern states had the largest increase in the percent uninsured. Thus, despite economic prosperity, the numbers and rates of the uninsured continue to rise. Principally affected are children and young adults, poor and middle-income families, blacks, and Hispanics.