Given school psychology's longstanding workforce shortages, mentorship may be an invaluable mechanism for supporting current and future school psychologists. To advance the literature in this area, we conducted a systematic review of mentoring research in school psychology. Through a comprehensive search of peer-reviewed scholarship, we identified 16 empirical studies published between 1988 and 2020 that directly examined mentoring. We then performed a qualitative thematic synthesis of their findings. Results indicated several benefits of mentoring, including support for mentees' career planning and psychosocial well-being. All studies were cross-sectional, and the majority did not consider the intersection of race and ethnicity with mentoring experiences; however, several described barriers to mentoring for individuals with racial, ethnic, sex, and gender minoritized identities. Findings indicate a need for more methodologically diverse research that centers the voices of mentors and protégés from traditionally marginalized backgrounds. Implications for reconceptualizing mentoring research and practice are discussed.