Information is presented on the pollutant control devices and methods most commonly used by the majority of the industries, processes, and facilities grouped under the Source Classification Categories as defined by the National Emissions Data System of the Environmental Protection Agency. Data for each category include the name of the source classification category; the source classification code; the control equipment identification number; the mean control device efficiency for particulates, sulfur dioxide, nitrogen oxides, carbon monoxide, and hydrocarbons; the range of observed control efficiencies; and the data source from which the information was obtained. These data are intended to be used in the preparation of emission inventories or other similar studies and do not necessarily reflect the extent of pollutant control at any single facility.