Co-rumination, or excessive discussion of problems within friendships, has been associated with internalizing symptoms and is especially prevalent among adolescent girls. Eighty-three early adolescent girls participated in a prospective study further examining this construct. Co-rumination was positively correlated with depressive symptoms and positive aspects of friendship, but did not predict longitudinal changes in depressive symptoms. Co-rumination was negatively related to social anxiety when controlling for depressive symptoms. Co-rumination correlated positively with romantic experiences, and the two interacted to predict longitudinal changes in depressive symptoms, implying that co-rumination may only be depressogenic under certain circumstances. Theoretical ramifications for the construct of co-rumination and interpersonal aspects of adolescent internalizing symptoms are discussed. (Contains 1 figure and 2 tables.)