This paper uses data from the Current Population Surveys for 1980 through 2011 to review trends in health-insurance coverage rates for low-wage workers (defined as workers in the bottom fifth of the wage distribution in each survey year). In 2010, over 38 percent of low-wage workers lacked health insurance from any source, up from 16 percent in 1979. The biggest reason for the decline in coverage is the erosion of employer-provided health insurance, either through a worker's own employer or as a dependent on another family member's employer-provided policy. Over the last three decades, the role of public insurance in providing coverage for low-wage workers has increased, though not nearly enough to offset the declines in private insurance. In 2010, about 10 percent of low-wage workers had coverage through Medicaid, double the share in 1979. While a great deal of uncertainty still surrounds the Affordable Care Act (ACA) and its likely impact on employers and workers, reasonable estimates based on consensus projections suggest that the ACA will have a substantial positive effect on health-insurance coverage rates for low-wage workers. Even so, the ACA will likely leave an important share of low-wage workers, especially low-wage Latino, African American, and Asian workers, as well as many immigrant workers, without coverage. At the same time, if the ACA is blocked -- in the courts or in Congress -- there is every indication that coverage rates for low-wage workers will continue their long, steady decline.