Student teachers commonly report encountering emotional challenges in work placements during teacher education. Even so, the perspective of mentoring teachers has been given little attention regarding the student teachers' emotional challenges. In this study, the authors' aim is to investigate what mentoring teachers perceive to be the emotional challenges student teachers face and what support they think they can offer student teachers. A sample of 25 Swedish mentoring teachers participated in an interview study. According to the findings, the mentoring teachers reported three main emotional challenges that they perceived that student teachers encounter: conflicts with/among pupils, encountering diverse pupil populations and dealing with failure. Mentoring teachers' reports can be understood in the light of their idea of what work placement should be. Their rationales included the need for student teachers to be either exposed to 'reality' or protected from worst-case scenarios.