This book outlines the key problems associated with the intersections of assessment, learning and teaching, and presents guiding principles to effective assessment that schools can follow in order to optimise student outcomes. Addressing challenges such as competing conceptualisations of assessment, the burden of responsibility on teachers and conflicting views of what effective assessment actually is, this book provides an in-depth analysis of these problems, how they are explored, what factors influence them and their implications for learning and teaching. It proposes practical solutions to address these challenges, supported by 29 case studies that capture examples of practice from Asia, Europe, the USA and Australia. The book concludes with the key features of the effective implementation of assessment reform, based on findings from a variety of scenarios, across different contexts and levels of education. Providing critical insights and practical guidance, this book is an essential reference for teachers, school leaders and postgraduate students of education.