This study evaluated the effectiveness of a group mentoring program that included components of empirically supported mentoring and cognitive behavioral techniques for children served at a community mental health center. Eighty-six 8- to 12-year-old children were randomly assigned to either group mentoring or a wait-list control group. Group mentoring significantly increased children's reported social problem-solving skills and decreased parent-reported child externalizing and internalizing behavior problems after controlling for other concurrent mental health services. Attrition from the group mentoring program was notably low (7%) for children. The integration of a cognitive behavioral group mentoring program into children's existing community mental health services may result in additional reductions in externalizing and internalizing behavior problems. (Contains 4 tables and 1 figure.)