Mentoring is widely believed to be beneficial to mentors and mentees in the teacher education context. However, mentoring as a tool for strengthening professional knowledge is not without barriers hindering its effectiveness. This paper explores common barriers in mentoring, drawing on studies conducted in Croatia, Ireland, and Scotland which have been re-analyzed for this paper. The two studies conducted in Scotland used a mixed-methods approach, the Croatian study was conducted using a quantitative approach, while the Irish research employed a qualitative strategy. Data from the four published studies were re-analyzed and integrated using a qualitative thematic approach with three groups of themes emerging as the most common barriers to mentoring in teacher education. These groups of themes are: interests, values and motives; power, status and position; and information and communication. The study explores these themes and concludes with the implications for stakeholders, including school management, universities, and student teachers.