Introduction: Early adolescence is a developmental period in which peer victimization, bullying, relational aggression, and social exclusion are particularly prominent. As these behaviors have long-term implications for children, in this study, we investigated early variations of prosocial behaviors as one of the critical precedents that shape youth's subsequent peer relational outcomes. Specifically, we identified different profiles of prosocial behaviors in middle childhood (Grade 4) and related these profiles to peer relationships in early adolescence (Grade 6). Method: Using longitudinal data from the NICHD Study of Early Child Care and Youth Development (N = 914; 52% girls), a three-step latent profile analysis was conducted on Grade 4 prosocial behaviors, which were then related to Grade 6 teacher-and student-rated peer relationships (e.g., relational aggression). Results: Four patterns of prosocial behaviors emerged: low prosocial (18%), high prosocial (67%), primarily friendly (8%), and primarily kind (7%). These four patterns of prosocial behaviors were differentially related to later problematic peer relationships: Low prosocial youth demonstrated the most problematic peer relationships (Mdiff = 0.36-0.93, all p < .001). Primarily friendly (but not kind) youth displayed more general and relational aggression (Mdiff = 0.22, SE = 0.07, p = .002; and Mdiff = 0.18, SE = 0.06, p = .006, respectively). Conclusion: Both low prosocial and primarily friendly youth are at risk for displaying peer-related problems; interventions that build prosocial behaviors in youth with a low prosocial or primarily friendly profile may help prevent problematic peer relationships at early adolescence.Early adolescence is a developmental period in which peer victimization, bullying, relational aggression, and social exclusion are particularly prominent (Hanish & Guerra, 2004;Karriker-Jaffe, Foshee, Ennett, & Suchindran, 2008). When tracing the roots of early adolescent problematic peer relationships for prevention purposes, middle childhood prosocial behaviors have been identified to be one of the critical precedents that shape youth's subsequent social developmental outcomes (Eisenberg, Spinrad, & Knafo-Noam, 2015, pp. 1-47). To better understand these processes and to improve prevention focused interventions, the current study examines children's prosocial behaviors-defined as actions and voluntary behaviors geared toward benefiting another (Eisenberg. et al., 2015;Hastings, Zahn-Waxler, Robinson, Usher, & Bridges, 2000)-either as being protective or a risk for problematic peer relationships during early adolescence.Children who have tendencies to engage in prosocial behaviors are shown to have a variety of competencies that reduce social