This study investigated gender differences in the moderating and mediating effects of responses to stress on the association between perceived peer stress and symptoms of psychopathology. A sample of 295 middle school students (63.7% female; M(age) = 12.39 years, SD = 0.99) completed self-report surveys on stress, coping, and behavioral problems. Involuntary responses to stress (e.g., physiological arousal, intrusive thoughts, impulsive action) mediated the association between perceived stress and anxiety/depression and aggression for girls and for boys. Disengagement coping (e.g., denial, avoidance) partially mediated the association between peer stress and anxiety/depression for boys and for girls. In contrast, disengagement coping mediated the association between peer stress and overt aggression for boys only. Finally, engagement coping (e.g., problem solving, emotion regulation, cognitive restructuring) buffered the indirect effect of peer stress on symptoms of psychopathology for girls only. Implications for prevention and intervention efforts are discussed.