Book excerpt: The book focuses on the extension of quality-assured measurement and metrology into psychological and social domains. This is not only feasible and achievable, but also a pressing concern. Significant progress in developing a common conceptual system for measurement across the sciences has been made in recent collaborations between metrologists and psychometricians, as reported in the chapters of this book. Modeling, estimation, and interpretation of objectively reproducible unit quantities that support both general comparability and adaptation to unique local circumstances are demonstrated in fields as diverse as artificial intelligence, justice, and beauty perception.