Despite findings indicating the importance of non-parental adults in the lives of youth, there is little research on these relationships, including those that occur in the context of youth mentoring. Compounding this problem is a positive slant taken towards youth mentoring in the media, often unsubstantiated by empirical evidence. This article outlines the research on youth mentoring by focusing on comprehensive literature reviews and evaluations of factors that influence the effectiveness and closeness of mentoring relationships. Review articles come to different conclusions about mentoring, in part because of differential emphasis on particular research findings. Further research indicates the importance of relationship duration and structure, as well as mentor skills, on youth outcomes. Implications for youth mentoring practices, including utilizing empirically-based mentor training, program implementation and evaluation of services, reducing volunteer attrition, and connecting youth mentoring with other services, are discussed.