Both age and cohort effects are examined, utilizing incidence and prevalence data categorized by race, social class, and place of residence. Within years there are few consistent, significant differences in the incidence of delinquency by any of the demographic variables analyzed. Significant race and social class differentials exist, however, in the prevalence of assaultive crimes among the panel, with substantially higher proportions of black and lower-class females reporting involvement in violent behavior for three of the five years. Strong cohort effects are observed for all delinquency measures. In general, the incidence and prevalence of serious female delinquency appear to decline with age, and the 15-17-year-old females in 1980 are significantly less involved in delinquency than their same-age peers were in 1976. (Publisher abstract)