This work analysed which profiles of counsellors' supportive and interpretative actions emerged in two group counselling interventions designed to promote mentalisation in underachieving university students. The Psychodynamic Intervention Rating Scale was used to analyse this and the level of depth of defence interpretations. Two outcome measures were administered to analyse student mentalisation and their academic achievements. Process findings showed that supportive actions were used for the most part in both counselling interventions; however, only one group improved in terms of mentalisation and academic performance. In the good-outcome group, there were more defence interpretations, especially during the early sessions, and with a deeper level of elaboration. The innovative relevance of these findings and their implications for practice among counsellors are discussed.