Since 1997 professional diaries have been emphasized in teacher training at the University College of Borås. This project is based on our experiences that we need better methods to promote students’ diary-writing, their collective reflection, and the roles played by mentors. The results show that students need more support in their use of the diary and that reflection is viewed as the glue that joins the professional diary, the education at the college and at teaching placements, and the mentoring activities. Both mentors and students report that they have changed their views on diary-writing.