The extent to which mentor teachers are able to address mentees' individual needs is an important factor in the success of mentoring. A two-dimensional model of mentor teacher roles in mentoring dialogues, entitled MERID, is explored empirically. Data regarding five aspects of mentoring dialogues were collected, using a sample of 20 transcriptions of mentoring dialogues, in which 112 topics were discussed and 440 mentor teacher utterances emerged. Correlations between the five aspects were determined and a cluster analysis was conducted. There is empirical support for the model. It is a useful framework to promote reflection on mentor teachers' supervisory behaviour.