This study examined longitudinal associations between adolescents' and their friend's depressive symptoms and depressogenic attributional style. Participants included 398 adolescents in grades six through eight at the outset of the study. Adolescents completed peer nominations to identify reciprocated and unreciprocated best friendships as well as measures of depressive symptoms and depressogenic attributional style at an initial time point, and again 11 months later. Results revealed that best friends' reported level of depressive symptoms was prospectively associated with adolescents' own depressive symptoms and with adolescents' depressogenic attributional style. Moderator effects suggested that friends' attributional styles were prospectively associated with adolescents' own attributional styles for those involved in reciprocated friendships. Lastly, findings offered preliminary support for adolescents' Time 2 depressive symptoms as a mediator of the association between friends' depressive symptoms and adolescents' attributional style. Findings have important implications for cognitive and interpersonal models of adolescent depression, as well as the study of peer contagion effects. KEY WORDS: depression; friendship; attributional style.