PRCCD is funded by the Office of Juvenile Justice and Delinquency Prevention and includes the Denver Youth Survey, the Pittsburgh Youth Study, and the Rochester, N.Y., Youth Study. Data collection began in 1987-88. The 4,500 participants in the 3 cities were regularly interviewed during that period, and their lives recorded in detail to provide information about juvenile delinquency, drug use, and mental health problems. Research during 1995-96 revealed that early juvenile delinquency and drug use increased the probability of being a school dropout. In Rochester and Denver, early delinquency and drug use also increased the probability of adolescent pregnancy, parenthood, and independent living. The onset of violence in males accelerated between ages 11 and 16. Predictors of the onset of violence in males after age 13 were a high anxiety score, a lack of guilt feelings, inconsistent discipline by the parent, and physical punishment by the parent. Depressed mood and the presence of hyperactivity were among the best correlates of onset of violence at some time. Victims of gun violence or homicide tended to be serious delinquents and had engaged in gang fights and drug selling. Victims tended to carry a hidden weapon and to own a gun. About one-fourth of the males in the three studies admitted to having sold marijuana by about age 18; 1 in 10 reported selling other illicit drugs. Other findings focused on gangs, factors influencing delinquency in different settings, arrest and subsequent delinquency, adolescent fatherhood, and precipitating factors of adolescent pregnancy in females. Tables, figures, and chapter reference lists