The purpose of this paper is to assess the predictive utility of several measures of the overall state of societal systems, as well as to determine the degree of overlap of the different measures. Data for 74 nations representing all geographic areas of the world are presented and analyzed. The 5 measures of societal systems chosen for comparison are the power-tool measure, energy consumption, human resource development index, index of societal differentiation, and gross national product per capita. The 5 societal sectors considered in constructing differentiation indices are political, economic, education, social welfare, and communication. The authors conclude that all the measures are not apparently measuring different aspects of society, but the measures appear to tap some similar underlying dimension of society. They suggest the use of an energy consumption measure as the best measure of societal modernization and of the status of societies relative to other societies. (PS)