The Causes and Correlates projects all use a similar research design. All of the projects are longitudinal investigations involving repeated contacts with youth during a substantial portion of their developmental years. In each project, researchers conduct individual, face-to-face interviews with inner-city youth considered at high risk for involvement in delinquency and drug abuse. Multiple perspectives on each child's development and behavior are obtained through interviews with the child's primary caretaker and, in two sites, through interviews with teachers. In addition to interview data, the studies collect extensive information from official agencies, including police, courts, schools, and social services.