The field of teacher education has long studied successful strategies for supporting pre-service teachers’ development. However, mentoring practices have received less attention than the nature and impact of other elements (e.g., coursework or school-university partnerships). In this article, we share the results of our systematic review of the literature on mentoring pre-service teachers in clinical settings in the United States. Themes from the synthesis include terminology clarification; the importance of the mentor teacher; characteristics of effective mentors; and mentor teacher training. We offer suggestions for future research on mentor teachers and mentor teacher practices in hopes of informing policy and practices in clinically-based teacher education.