The U.S. EPA has initiated a multi-phased study of the acid rain problem. As part of Phase I, Radian Corporation investigated SOa emissions and controls in the industrial sector. The scope of this 4-month study was limited to existing industrial sources of SO2 emissions in the Acid Rain Mitigation Study (ARMS) region. This region includes all of the states east of the Mississippi River, as well as Minnesota, Iowa, Missouri, Arkansas, Louisiana, North Dakota, South Dakota, Nebraska, Kansas, Oklahoma, and Texas. The objectives of the study were to (1) identify and characterize existing industrial sources of SO2 emissions, (2) identify the control techniques that can be used to reduce SO2 emissions from these sources, and (3) estimate the SO2 emission reduction potential and the associated costs in constant 1980 dollars based on application of these controls. Because of severe time limitations, only a portion of the SOa sources were investigated in detail. Simplifying assumptions were made about the balance of the SO2 sources studied. Time constraints also prevented an evaluation of the availability of low sulfur control options (i.e., physically cleaned coal and low sulfur fuel oil). In addition, since site visits were not made, the remaining useful lives of the sources were not determined and "average" flue gas desulfurization unit retrofit factors were estimated. Each of these considerations significantly affects both the potential SO2 emissions reduction and the associated costs. The results of the investigations conducted to meet each study objective are presented in the report. Recommendations concerning the use of these results are also discussed.