The Clean Air Act Amendments (CAAA) of 1990 instituted a historic experiment in emission allowance trading for sulfur dioxide (SO<sub>2</sub>). A necessary requirement for evaluating this experiment is an understanding of how the cost recovery rules and other guidance given to firms by state-level public utility commissions (PUCs) and elected bodies has affected compliance behavior. From the onset of the CAAA, there has been varied response by state policy-makers toward SO<sub>2</sub> compliance. This paper presents a compilation of these actions as they took shape in states that were affected by the SO<sub>2</sub> program. Our primary interest is on the proposals that emerged during the embryonic years of the allowance program, from 1990 to 1993, when investment plans for utilities affected by the first phase of the program beginning in 1995 were taking shape.