In this study, the authors examined whether concurrent associations between adolescent outcomes and disagreements with mothers, fathers, and best friends vary as a function of perceived relationship quality. Participants were 469 11- to 18-year-old youths from a culturally diverse community. Negative qualities of parent-adolescent and friend relationships were linked to adjustment problems (aggression, anxiety and depression, delinquency, and withdrawal). Positive qualities of parent-adolescent relationships were linked to school grades and adjustment problems. Nonlinear associations between conflict and adolescent outcomes were moderated by negative qualities of relationships such that increases in conflict from low to moderate levels were linked to (a) higher school grades for adolescents in better but not poorer quality relationships and (b) greater delinquency and withdrawal for adolescents in poorer but not better quality relationships.