Traditions of Didaktik and Fachdidaktik in Scandinavia will be elucidated as a starting point. Special interest will be given to the development of subject-matter Didaktik, and the Didaktik of art subjects (especially music) will be exemplified. Subject-matter Didaktik and the field of an educational subject will be seen as a field of relations (a) between the basic subject (for art subjects dimensioned into science, craft and art aspects) and general pedagogical and general Didactic concerns, and (b) between Didaktik as a praxis oriented and a theoretically oriented discipline. Distinctions and concepts will be developed to capture and describe these relations and mutual dependencies. In the praxis-theory dimension a distinction will be made between Didaktik in its prescriptive and normative aspect and in its descriptive and analytic dimension (““Didactology”). In the subject-oriented dimension distinctions will be made between levels of practica, didactica, scientia, ars and natura, and interrelationships between these levels will be shown as depending on and resulting in distinct subject views. A conclusive point will be subject-matter Didaktik (Fachdidaktik) as a research area characterised as an integral (as opposed to an additive) but relatively autonomous discipline based on reciprocity and parity between a subject-oriented didactology and the basic scientific subject itself.