According to the Epidemiologic Catchment Area (ECA) study--one of the largest investigations of the prevalence of mental disorders ever conducted--anxiety disorders affect more than 7% of adults in the United States. Women, individuals under age 45, those who are separated or divorced, and those in low socioeconomic groups all have a higher rate of anxiety than individuals in other groups. This article will present prevalence rates of anxiety disorders based on data from the five ECA sites--New Haven, Conn; Baltimore, Md; St Louis, Mo; Durham, NC; and Los Angeles, Ca.