For the last two decades mentoring as a developmental relationship has been investigated and elaborated on by several researchers. In our study, 382 pre-service teachers answered questions about aspects of developmental mentoring relationships. Using structural equational modelling, we investigated relations between mentors' effort, self-development orientation and theory-use as possible predictors of perceived developmental support. Our findings indicated that pre-service teachers' perceptions of school mentors' effort and self-development orientation were positively associated to their perceptions of developmental support in mentoring. Mentors' emphasis on theory in mentoring discussions was negatively, although weakly, related to pre-service teachers' perceptions of receiving developmental support.