Data were obtained from the California Department of Justice's Crime and Delinquency in California Survey and its supplement, California Criminal Justice Profiles which present arrest statistics of age, race, ethnicity, sex, and offense. Arrest rates per 100,000 population by age were used as crime trend measures. Arrest trends were analyzed for all felonies, violent felonies, and homicide. The four age groups of interest were 10-17 years, 18-29 years, 30-49 years, and 50-69 years. Youth felony arrest rates declined by 40 percent over the 1975-1998 period, while felony arrest rates for adults over 30 years of age increased. In 1978, the average violent crime arrestee was 21.5 years, while in 1998 the average violent crime arrestee was 27.7 years. Juveniles comprised 30 percent of California's felony arrestees in 1978 but comprised less than 15 percent in 1998. Homicide and other violent crime arrests increased sharply among juveniles, from a low in 1984 to a peak in 1991. However, the popular claim that the increase in juvenile homicide and violent crime signaled a more violent teenage generation was not supported. Murder and violent crime trends represented a periodic cycle that was not sustained. Of particular significance, these cyclical variations were not driven by demographics; homicide and violent crime increases in the 1980's and 1990's occurred as California's teenage population was declining. Further, declining violent crime rates during the middle and late 1990's occurred while the teenage population was rising. The authors conclude that the findings dispel pervasive beliefs about the scope of youth crime and indicate the need for policymakers and the media to re-examine popular assumptions about youth crime and youth crime policies. An appendix contains statistics on California arrest rates by age, race, and sex per 100,000 population. 9 references, 13 tables, and 4 figures