This book examines the history of formative assessment in the US and explores its potential for changing the landscape of teaching and learning to meet the needs of twenty-first century learners. The author uses case studies to illuminate the complexity of teaching and the externally imposed and internally constructed contextual elements that affect assessment decision-making. In this book, Box argues effectively for a renewed vision for teacher professional development that centers around the needs of students in a knowledge economy. Finally, Box offers an overview of systemic changes that are needed in order for progressive teaching and relevant learning to take place.