This study longitudinally examined associations between parent and peer relationships, childhood maltreatment, and adolescents’ psychopathology. We expected lower perceived parental relationship quality to predict greater symptomatology and higher perceived friendship quality to buffer this association, with greater buffering effects for maltreated participants. We assessed 545 participants (295 maltreated, 250 non-maltreated; 60.2% male; 52.8% Black, 27.5% White, 12.8% Bi-racial, 13.4% Latin@) across two timepoints (Wave 1, Mage = 13.8 years, Wave 2, Mage = 16.2 years). Department of Human Services records indicated maltreatment status prior to Wave 1. Adolescents self-reported Wave 1 parental relationship and friendship quality and Wave 2 internalizing/externalizing symptoms. Parental relationship quality did not predict psychopathology, and this association did not differ by maltreatment status. We found a significant three-way interaction between maternal relationship quality, maltreatment, and friendship quality on internalizing (β = .10, p = .037) and externalizing (β = .12, p = .010) symptoms. For non-maltreated adolescents, parental relationships and friendship quality differentially predicted symptomatology. Maltreated adolescents with low maternal relationship and friendship quality exhibited the most symptoms, whereas those with low maternal relationship quality and high friendship quality exhibited the least. Findings invite inquiry into parent and peer relationships’ differential roles in adolescents’ psychopathology.