In order to support at-risk adolescents in their transition to high school, a school-based mentoring program was implemented for a group of 9th and 10th grade students. Due to the need for greater clarity regarding the impact of school-based mentoring on youth outcomes, a quasi-experimental study was conducted to examine the impact of one-to-one mentoring on students' social-emotional health. Strengths-based survey data were collected from participants at pre-intervention and post-intervention. Findings suggested that school-based mentoring is a promising practice for improving the social-emotional strengths of adolescents and/or protecting them from the risks associated with adolescence. (Contains 3 tables and 6 figures.)