This document reviews the results of a study of five Ohio Supreme Court cases concerning the equalization of property assessments among the various classes of real property: commercial, industrial, residential, and agricultural. Each of the decisions--occurring between 1964 and 1980, and involving the Park Investment Company--is briefly summarized with respect to its effect upon property assessment and taxation at the state level (determined through analysis of sales ratio studies). Each case also is discussed in terms of its effect on Richland County (Ohio) and, specifically, on the Mansfield school district in Richland County. In all cases, the court had difficulty in implementing its concept of property equalization because of the complexities of the problem and such political and financial implications as the required implementation by either the state legislature, the General Assembly, or the Board of Tax Appeals. Seventeen tables are included, and 42 footnotes are appended. (IW)