This book reports the design, execution, and results of a cross-national study of classrooms in eight countries. Students were administered tests and completed questionnaires at the beginning and the end of the study. Teachers also completed questionnaires. Classrooms were visited by trained observers on the average of eight times during the study. The data were analyzed in a variety of ways: simple summaries, sequential analyses, and multivariate analyses. The results of these analyses are presented and discussed. Conclusions based on these findings as well as recommendations for further research are presented.