This book highlights the impact of policy and politics on assessment across the globe. With contributions from England, the Irish Republic, Northern Ireland, Norway, Sweden, Switzerland, and Wales, it explores state-led assessment policies and practices that have been the subject of much debate. We are experiencing a shift from using assessments — especially national tests — as measurement instruments designed to produce information, to a reliance on tests to influence policy and instruction. Once tests become high stakes — for students, teachers, and schools — even those that might have been reasonable monitors of educational success can lose dependability and credibility. However, not all countries’ assessment policies follow the same model and the contributors explore and analyse a range of different national (and supra-national) assessment policy approaches and perspectives. The chapters identify the impetus behind changing assessment policies and practices and analyse ways forward and innovative approaches. Readers can draw their own conclusions about which model(s) can provide the best outcomes for learners – surely the most important part of the equation. This book was originally published as a special issue of Assessment in Education: Principles, Policy & Practice.