This book proposes a new approach to differentiating between developing countries in the context of special and differential treatment (SDT) in the World Trade Organisation.Offering unique insights into SDT reform in the WTO, the book proposes the method of differentiated differentiation and demonstrates its operationalization using the WTO Customs Valuation Agreement. Through identifying key indicators to categorize constraints faced by developing countries, the book establishes objective criteria to depoliticize access to SDT. Promoting a case-by-case approach, the book also employs a statistics-based score procedure to determine a threshold for graduating countries out of SDT. Through flexible tracking and evidence-based arguments, the book provides a transitional method of reform which maintains full compliance with WTO members’ obligations.The book will be of importance to academics and students of international law, especially those with an interest in international trade law and the WTO, as well as legal professionals and policymakers.