This study examined data from the Institute of Education Sciences' evaluation of school-based mentoring (SBM) programs to establish a causal relationship between SBM and reduction of the academic achievement gap between African American and White middle school students. Participation in SBM improved the academic performance of all students. The findings demonstrated a sizable increase in African American students' grade point average as a result of same-race mentoring. Implications for school counselors seeking to reduce the achievement gap are discussed.