Competence diagnostics: a new buzzword associated with many hopes. The interest in this topic stems, on one hand, from the weaknesses of conventional diagnostic methods, such as issues with the validity and significance of previous assessments of learning prerequisites and outcomes. On the other hand, there are several new methods and approaches worth being informed about. The special issue of ZfE aims to clarify fundamental questions, present the current state of research, and showcase new approaches to competence diagnostics.