Examines whether there are gender differences in changes in the aggregate level and individual stability of conduct problems from early adolescence to early adulthood. Analyzes self-reported data from a study of Norwegian adolescents. Analyses showed that involvement in conduct problems for both genders peaked in mid-adolescence. In the long term, relative involvement was more stable for boys than for girls. (Contains 51 references, 5 tables, 1 figure, and 1 appendix.) (GCP)