Prior research on mentoring relationships outside of school does point toward relationship closeness and related indicators of the emotional quality of the mentor-protégé tie as important influences on youth outcomes. There is preliminary evidence that this may also be the case for School Based Mentoring (SBM), or at least that closeness promotes protégé and mentor perceptions of relationship quality. The overarching aim of this paper is to enrich the field's understanding of how volunteer mentors can best support the academic mission of schools. The central empirical analysis investigates whether emotionally closer relationships between mentors and protégés lead to better academic outcomes. The sample for the study consists of the students who participated in the randomized control trial of the Big Brothers Big Sisters of America (BBBSA) SBM program during the 2004-2005 school year. Study participants were recruited by 10 BBBSA study agencies across the country, each with four or more years of experience in SBM. Evidence is found that a close mentoring relationship positively affects academic performance. Effect sizes, obtained by dividing the impact coefficients reported in the table by the standard deviation of the appropriate outcome measure, range from 0.13 standard deviations (for overall academic performance and scholastic efficacy) to 0.18 standard deviations (for completeness of schoolwork), and are consistent across alternative specifications. A table is appended.