The paper will first clarify three terms: “didactics”, “curriculum” and “subject didactics“, mainly within the German frame of reference and its historical development. It will raise questions like: Why compare two or more didactics for different subjects? What are the driving forces behind attempts to define a common core of research questions, shared methodologies, practical issues? What are theoretical overlaps between all subject didactics? How is that linked to the self-definition as a discipline and teacher education? We will position didactics between academic disciplines and educational sciences, related to both of them, but also independent from them. Subject didactics as individual disciplines work on their own segment of reality each, they mediate between the subjects involved and content; their main concern is the identification of the educational potential in teaching and learning a specific topic or subject-matter area (fachbasiertes Bildungspotential; Bayrhuber et al. 2012). Accordingly, these educational “outcomes” (im, am und durch das Fach; Vollmer 2012) will be identified and linked to that of other subjects – the beginning of an intimate rapprochement, cooperation and common goal setting, the birth of generalised or general subject didactics (didactiques disciplinaires généralisées) - which transforms into a singular (meta-)discipline as commonalities grow.