Where educational programmes drawn up on the basis of the findings of didactics in the relevant field exist, educational research can focus on how far the actual realisation of the programme corresponds to the intentions of the programme authors. It can also focus on the relationship between various aspects of the implementation of the programme and student outcomes. Different aspects of the implemented curricula can be researched. In this way curricula writers can get feedback on how the programme can be improved, educational policy-makers and teacher trainers can obtain information about the kind of educational support teachers need to improve practice, and teachers can obtain evidence-based recommendations on which practices are in accordance with the inten-tions of curricula writers and if possible, what practices bring better educational outcomes of students.
This overview study presents an ap-proach to research on the correspondence between the intentions of an intervention or educational policy and the reality of its implementation, here defined as „fidelity of implementation“.
The study defines the concept of fidelity of implementation, assembles the arguments for the investigation of fidelity of imple-mentation and describes its methods. It is concerned with the relationship between fidelity of implementation and educational outcomes for students and offers a short review of research in this area. It describes in detail an example of the qualitative study of fidelity of implementation. In addition, the study describes the factors that influence the level of fidelity of implementation identified in foreign research.