Research has shown that the access to explicit criteria can promote student learning by making expectations explicit and by supporting students in identifying significant dimensions of quality in task performance. The aim of the study was to investigate how explicit criteria can support pre-service teachers' understanding of relational competence. The research design was an intervention study. Digital video was used as a tool for pre-service teachers to analyze interaction in simulated situations focusing on the relationship between teacher and students. Sources of data used were 1) pre-service teachers’ written analyzes before and after the access to explicit criteria, and 2) transcripts from focus-group interviews, concentrating on pre-service teachers’ perceptions of how the access to criteria affected their understanding of relational competence. The findings indicate that the access to explicit criteria positively affected pre-service teachers’ capacity to discern significant dimensions of relational competence, as well as their understanding of how trustful relationships between teachers and students can be created and maintained. All pre-service teachers perceived that the access to explicit criteria had helped them to gain a deeper understanding of relational competence and how relational competence can be observed and analyzed in interaction. A conclusion that can be drawn from the study is that the pre-service teachers, through access to criteria, developed new interpretative tools to communicate about relationships and teachers’ relational competence.