This report details a study combining qualitative and quantitative research tools to compare the functioning of schools in China, Guinea, India, and Mexico and in different development contexts within each country. The focus of the analysis was on the critical factors determining the quality of the interactive process taking place in schools, how these factors relate to student performance, and how this performance can be improved. The report is organized in three parts. Part 1 contains a general description of the study, its methodological approach, the research objectives, and the contrasting localities selected in each country. Part 2 compares the principal findings of the case studies, with chapters dealing with problems relating to the interactions between the school, parents, and pupils; the material conditions of teaching; teachers' problems; how schools operate; and the teaching-learning process. This part also analyzes the communication and numeracy skills of pupils in the fourth grade and sixth or final grade of primary schooling. Part 3 summarizes the major findings and examines implications for planning and management. Appended are results of regression analyses examining variations in achievement scores between learners in Mexico, India, and Guinea. Contains 79 references. (KB)