This study aimed to (a) identify mentoring quality profiles based on characteristics of informal mentoring relationships, (b) examine how mentor and youth demographic characteristics were related to the profiles, and (c) investigate whether the profiles were related to youth’s academic outcomes. Participants were 411 ninth-grade urban, low-income students. Mentors were comprised of older siblings, extended family members, and non-familial adults. Using cluster analysis, we identified two mentoring quality relationship profiles: (a) less close and growth oriented and (b) closer and more growth oriented. Boys were more likely to have less close and growth-oriented relationship profiles or to be in the non-mentored group compared with girls. Univariate tests showed differences among relationship profile groups and non-mentored groups on intrinsic motivation, educational aspirations and expectations, perceived economic benefits, and limitations of education and grade point average (GPA). The study reveals the importance of taking a within-group, person-centered approach when examining mentoring relationships.