This chapter introduces what constitutes the chemistry didactics knowledge a chemistry teacher needs to effectively teach chemistry. It takes up general pedagogical learning theoretical perspectives and draws out connections between these and chemistry teaching and learning. Emphasis is put on existing teacher knowledge characterizations (teacher knowledge elements), their nature, attainment (development) and the envisioned application of these knowledge elements in chemistry classrooms. By describing the various components of a teacher’s knowledge for teaching, the chapter aims to enable both teachers and teacher trainees to visualize and appreciate the need for and relevance of chemistry didactics training for chemistry teachers.