Why a dossier on the validity of research in science and technology didactics (STD)? After all, in many disciplines, each publication project is limited to research and peer review. But it turns out that didactics have a certain number of shortcomings: they claim to say something about school, known as a sensitive societal subject; they claim, particularly through their methods, that they belong to the human sciences which are devalued by the smells of scientism compared to the so-called "hard" sciences; they are young and have developed, at least initially, in tension with the institutions. The purpose of this dossier is not to settle once and for all this question of the validity of STD research, but to help place this problem in its historical and scientific context and to call on researchers in the field to discuss this subject. The contributions that structure this dossier offer an interesting variety for discussing the validity of the results of the STD. Thus, the first two articles present a methodological perspective on research, one on the validity and reliability of a questionnaire tool and the other on the validity of the results produced by a study of teachers' responses to open-ended questions. The third article takes the form of a methodological meta-analysis and discusses the functions of case studies in STD research.