Fifth-graders' (N = 162; 93 girls) relationships with parents and friends were examined with respect to their main and interactive effects on psychosocial functioning. Participants reported on parental support, the quality of their best friendships, self-worth, and perceptions of social competence. Peers reported on aggression, shyness and withdrawal, and rejection and victimization. Mothers reported on psychological adjustment. Perceived parental support and friendship quality predicted higher global self-worth and social competence and less internalizing problems. Perceived parental support predicted fewer externalizing problems, and paternal (not maternal) support predicted lower rejection and victimization. Friendship quality predicted lower rejection and victimization for only girls. Having a supportive mother protected boys from the effects of low-quality friendships on their perceived social competence. High friendship quality buffered the effects of low maternal support on girls' internalizing difficulties.