Stress is known to amplify the link between pubertal timing and psychopathology. However, few studies have examined the role of peer stress as a context for this link. The present study examined the interaction between perceived pubertal timing and peer stress on symptoms of psychopathology in early adolescence. The sample consisted of 264 students (63 percent female; M (age) = 12.40, SD = 1.00; 55 percent Caucasian, 23 percent African-American, 7 percent Latino, 11 percent biracial and 4 percent other). Higher peer stress was associated with symptoms of anxiety/depression; this effect did not vary by timing or gender. However, early-maturing girls with high peer stress demonstrated higher rates of relational and overt aggression compared to other girls. Findings also suggested that late-maturing boys with high stress are at risk for aggression problems; however, due to the small number of boys, analyses were exploratory. Overall, results suggest that developmentally salient contexts as indicated by stressful peer experiences may pose unique threats to early maturing girls and possibly late-maturing boys. (Published Abstract)