Accumulated research findings in past decades have led to the common knowledge that teachers’ professional knowledge is essential to effective classroom instruction. However, there is still very limited understanding about the nature of teachers’ expertise in mathematics instruction. Expertise in Mathematics Instruction addresses this need clearly and concisely. In particular, it examines all aspects of emphases employed to characterize the nature of expertise in mathematics instruction from both researchers’ and practitioners’ perspectives. Moreover, with research contributions from both the East and the West, this book also examines ideas pertinent to fostering and demonstrating expertise in mathematics instruction within different system contexts. This book will raise questions and issues for mathematics education researchers to guide a critical examination of what can be learned from other education systems. Expertise in Mathematics Instruction builds on its theoretical and methodological approach with contributions from international experts in the field. Additionally, a review of related research from mathematics education serves as an introduction to the new research in both Eastern and Western settings. Concluding this resource is a reflection on the benefits of this international collaboration and possible research directions for the future. The final chapter cohesively joins traditional and current research for action. Expertise in Mathematics Instruction is of interest to researchers in mathematics education, mathematics teacher educators, and mathematics educators.