This report is intended (1) to identify social, economic, and political factors that account significantly for differences between national systems of education to draw up national socioeconomic and educational profiles of 20 participating countries, and (2) to relate these characteristics to cognitive learning outcomes as measured by achievement tests in science and reading comprehension. Chapter 1 presents a work chronology and a general account of the problems of data acquisition and analysis encountered during the study. Chapter 2 presents a series of data profiles on each country's educational and social system. Chapter 3 presents social and educational data organized by variable, rather than by country. Chapter 4 reviews and summarizes the major findings of the study and discusses the study's implications for future research and for national policy and planning. The study focuses on the countries of Australia, Belgium, Chile, England and Wales, West Germany, Finland, France, Hungary, India, Iran, Ireland, Israel, Italy, Japan, the Netherlands, New Zealand, Scotland, Sweden, Thailand, and the United States. (Author/JG)