This article reports the findings of a review of the international research literature on mentoring beginning teachers. Research identifies a range of potential benefits and costs associated with mentoring, and suggests that the key to maximising the former and minimising the latter lies in the realization of a number of conditions for successful mentoring, such as the effective selection and preparation of mentors. We also highlight a number of limitations in the current evidence base on beginner teacher mentoring. Some implications, for the practice of teacher educators, for policy-makers and for future research, are considered.