Foreword, T. Plomp. Studying learning, growth and instruction cross-nationally: lessons learned about why and why not to engage in cross-national studies, L. Burstein. Overview of the longitudinal version of the Second International Mathematics Study, K.J. Travers. Classroom processes: conceptual considerations and design of the study, T.J. Cooney. Characteristics of schools, teachers and students, D.F. Robitaille. The identification and description of student growth in mathematics achievement, W.H. Schmidt, R.G. Wolfe & E. Kifer. Understanding patterns of student growth, E. Kifer, R.G. Wolfe & W.H. Schmidt. The distribution of instructional time to mathematical content: one aspect of opportunity to learn, W.H. Schmidt. Contrasts in the teaching of selected concepts and procedures, D.F. Robitaille. Content representation in mathematics instruction: characteristics, determinants and effectiveness, C.C. McKnight & T.J. Cooney. Teachers' strategies and students' achievement, D. Robin. Pedagogical practices and student heterogeneity, L. Burstein. Opportunities, talents and participation, E. Kifer. Concomitants of growth in mathematics achievement during the population A school year, W.H. Schmidt & L. Burstein. Concluding thoughts: what we know, what it means, E. Kifer & L. Burstein. Index.