This report uses data from the March Current Population Survey to estimate the prevalence of disability among the non-institutionalized working-age (aged 25 through 61) civilian population in the United States, and for each state and the District of Columbia for the years 1981 through 1999. Two definitions of disability that are commonly used in the literature—work limitation and work disability—are utilized. The prevalence of work limitation and work disability varies greatly across states and over time. However, rankings by state and variation in prevalence over time are not dramatically affected by choice of definition.