This volume presents a set of studies that explore significant questions about mathematics teaching and learning, and illustrate new methodologies for the analysis of new questions about mathematics education. The data from the Second International Mathematical Study (SIMS) is the starting point for all of the material in this work. SIMS was one of the largest and most comprehensive data-collection effort on mathematics teaching and learning ever undertaken. Because of its scale, comparative cross-cultural perspective, conceptualization and design, its data offer an indispensable beginning point for the exploration of many of the fundamental questions that circle around mathematics teaching and learning, not only internationally, but in the United States as well.