We compared the mentoring experiences and mental health and behavioral outcomes associated with program-supported mentoring for 125 Aboriginal (AB) and 734 non-Aboriginal (non-AB) youth ages 6-17 participating in a national survey of Big Brothers Big Sisters community mentoring relationships. Parents or guardians reported on youth mental health and other outcomes at baseline (before youth were paired to a mentor) and at 18 months follow-up. We found that AB youth were significantly less likely than non-AB youth to be in a long-term continuous mentoring relationship. However, AB youth were more likely than non-AB youth to be in a long-term relationship ending in dissolution. AB youth were also more likely than non-AB youth to have been mentored by a female adult. AB youth were significantly more likely than non-AB youth to report a high quality mentoring relationship, regular weekly contact with their mentor, and monthly mentoring activities. Structural equation model results revealed that, relative to non-mentored AB youth, AB youth with mentors experienced significantly fewer emotional problems and symptoms of social anxiety. These relationships were not found for non-AB youth. Our findings suggest that mentoring programs may be an effective intervention for improving the health and well-being of AB youth.