This study examined whether mentoring influenced children's self-concept, anxiety, depression, and relationships with parents and peers over an 18-month period. We examined 31 mentored children (50% female) and a comparison group of 22 nonmentored children (50% female) at the beginning of a mentoring program in the fall of the fourth-grade year (mean age = 9.67) and again in the spring of the fifth-grade year (mean age = 11.25). In fourth grade, 53 children completed the Piers-Harris Children's Self-Concept Scale, the Revised Children's Manifest Anxiety Scale, the Children's Depression Inventory-Short Form, and the People in My Life questionnaire, and 41 children completed the surveys again in fifth grade. Six fourth-grade and six fifth-grade teachers completed the Student Behavior Survey. Paired-sample t-test analyses indicated meaningful improvement in only mentored children's self-concept and anxiety. However, neither mentored nor nonmentored children revealed improvements in depression or relationships. Teacher ratings of mentored children did not suggest behavioral changes in the predicted direction. We discuss these counterintuitive findings, along with suggestions for future research. (Contains 2 tables.)