Thinking systematically about teaching and learning in relation to the knowledge contents and domains structured in the curriculum traditionally belongs to the broad field of Didactics in European countries. Far from being unified, this field is characterized by its fragmentation and broad interest linked to the historical evolution of educational goals in national contexts, but also to the diversity of institutional solutions in education as an academic discipline and in pre- and in-service teacher training structures. Building on different research traditions for conceptualizing the relationships between teaching, learning and the contents taught/learnt, this book pursues a threefold aim: (i) it presents certain recent theoretical developments of Didactics and, more particularly, the development of general subject didactics and comparative didactics; (ii) it provides a sample of the diversity and complementarities of methodological approaches for the empirical study of teaching and learning in the classrooms; and (iii) it addresses certain societal challenges that didactic research faces in a changing world. This introduction first recalls some aspects of the development of research in Didactics in continental Europe to highlight the specificity and the complexity of this field. Then, we introduce the authors’ chapters, sketching the most salient relations between them within each part of this book.