The 1958 cohort committed about 130 more offenses per 1,000 study participants than did the 1945 cohort. However, this difference was slight compared to the differences in rates for specific offenses or offense types, particularly serious offenses. Thus, the two cohorts were similar only for relatively minor offenses, and the 1958 cohort had a significantly higher offense rate for index offenses and violent index offenses. Nonwhite in both cohorts committed more offenses than whites, although the race disparity was greater in the 1945 cohort than in the 1958 cohort. Lower socioeconomic status was also associated with higher rates of offending, with a stronger association in the 1945 cohort than in the 1958 cohort. Moreover, recidivists committed much more serious offenses than did one-time offenders, with a stronger disparity in the 1958 cohort than in the 1945 cohort. The data showed clearly that juveniles who commit only one offense are rarely involved in the more serious offenses. Tables