The sample consisted of 1,829 youth (1,172 males and 657 females) enrolled in the Northwestern Juvenile Project, which is examining the health needs and outcome for delinquent youth. Participants, who were 10 to 18 years old, were randomly sampled from intake at the Cook County Juvenile Temporary Detention Center (Illinois) between 1995 and 1998. The sample was stratified according to gender, race/ethnicity, age, and legal status. Data on deaths and causes of death were obtained from family reports or records and were then verified by the local medical examiners or the National Death Index. In comparing mortality rates for delinquents and the general population, all data were weighted by race/ethnicity, gender, and age. These weighted, standardized populations were used to calculate reported percentages and mortality ratios. Mortality ratios were calculated by comparing the sample's mortality rates with those for the general population of Cook County, controlling for differences in gender, race/ethnicity, and age. Overall, the mortality rate among delinquent youth was just over four times higher than that in the standardized general population of Cook County, with the mortality rate for delinquent females being eight times that of the general population. More than 90 percent of deaths among delinquent youth were homicides. The leading causes of death among youth in the general population were accidents, followed by homicide, suicide, and malignant neoplasms. The findings highlight the role of firearms in early violent deaths, with deaths from firearms affecting minority youth disproportionately, both in the sample and in the U.S. general population. Implications for public health policy are discussed, along with study limitations and future research. 2 figures, 3 tables, and 78 references