Studies have documented numerous positive effects of mentoring, but few studies have focused on mentor education and mentors' professional development and learning. In Norway, the focus on mentoring and mentor education has been visible in political documents and teacher education for several years. However, the scale of mentor education has been small, despite official documents requiring mentor education for all teachers mentoring pre-service teachers and newly qualified teachers. This mixed methods study investigated four Norwegian schools in which all teachers and leaders took a university-based mentor education as part of a university-school project. The study aims to bring awareness to mentor education and what expectations teachers have of it, along with what experiences and benefits teachers express after completing mentor education collectively. The data were collected using a quantitative survey (N = 83) and qualitative focus group interviews (N = 9). The results show that, despite having few expectations when starting, mentor education was experienced as important and useful for teachers because the knowledge and skills acquired are relevant in all facets of the teaching profession. Moreover, the results provide an indication of the benefits of taking mentor education collectively and developing professional learning communities of mentors.