This questionnaire study examined co-rumination (extensive discussion of problems, focusing on negative feelings) among third-, fifth-, seventh-, and ninth-graders and its relationship to positive friendship adjustment and problematic emotional adjustment. Responses indicated that co-rumination related to high-quality close friendships but also to aspects of depression and anxiety. Girls reported co-ruminating more than did boys, which helped to account for girls' more positive friendship adjustment and greater internalizing problems. (Author/KB)