This book explains the causal pathways, the mechanisms and the politics that define the quantity and quality of policy learning. A rich collection of case studies structured around a strong conceptual architecture, the volume comprises fresh, original, empirical evidence for a large number of countries, sectors and multi-level governance settings including the European Commission, the European Union, and individual countries across Europe, Australia, Canada and Brazil. The theoretically diverse chapters address both the presence of learning and its pathologies, deploying state-of-the-art methods, including process tracing, diffusion models, and fuzzy-set techniques.