How different mentoring approaches affect beginning teachers' development in the first years of practice

•Mentoring quality can be described as either constructivist or transmissive.•Constructs are reliably measured in a study with more than 700 beginning teachers.•Constructivist mentoring improves teacher efficacy, enthusiasm and job satisfaction.•Constructivist mentoring also reduces emotional exhaustion.•Transmissive mentoring barely affects the professional development of teachers in these respects.

This study examines the extent to which the quality of mentoring and its frequency during the first years of teaching influence teachers' professional competence and well-being. Analyses are based on a sample of more than 700 German beginning mathematics teachers who participated in a pre-test/post-test study over the course of one year. Findings indicate that it is the quality of mentoring rather than its frequency that explains a successful career start. In particular, mentoring that follows constructivist rather than transmissive principles of learning fosters the growth of teacher efficacy, teaching enthusiasm, and job satisfaction and reduces emotional exhaustion.