The purpose of the Project on Human Development in Chicago Neighborhoods (PHDCN) was to examine how families, schools, and neighborhoods affect child and adolescent development. This included understanding the causes and the pathways of juvenile delinquency, adult crime, substance abuse, and violence. The Project had a focus on studying problematic behavior as well as an interest in social competence. The long-term objectives were to create knowledge that would inform violence prevention strategies and help develop better approaches to the promotion of social competence in children from infancy to young adulthood. <br /><br /> The Project combined two studies into one comprehensive design. The first study was an intensive study of Chicago's neighborhoods including their social, economic, organizational, political, and cultural structures, and the changes that take place within these structures. This was achieved through data collection efforts at the community level, including a community survey of Chicago residents, interviews with neighborhood experts, systematic social observations involving block by block videotaping, and analyses of school, police, court and other agency records. The second study was a longitudinal cohort study involving seven randomly selected cohorts of children, adolescents, and young adults, looking at the changing circumstances of their lives and the personal characteristics that may lead them towards or away from a variety of antisocial behaviors. <br /><br /> PHDCN is organized as five components: 1) Longitudinal study with an embedded intensive study of infants (Infant Assessment Unit); 2) Community survey; 3) Observational study of neighborhoods; 4) Neighborhood expert survey; and 5) Administrative data. Neighborhoods were operationally defined as 343 clusters of city blocks from Chicago's 847 populated census tracts.<br /><br /> The Longitudinal Cohort Study consists of three waves of data collected over a period of seven years from a sample of children and youth and their primary caregivers. The study involves seven randomly selected cohorts of children, adolescents, and young adults, looking at the changing circumstances of their lives and the personal characteristics that may lead them towards or away from a variety of antisocial behaviors. The age cohorts include birth, 3, 6, 9, 12, 15, and 18 years. Participants were drawn from 80 neighborhood clusters and were selected through in-person screening of 40,000 dwelling units within the identified communities. A total of 8,347 participants were identified. In the first wave of data collection, 75% of the identified participants were interviewed. Questions assessed impulse control and sensation-seeking traits, cognitive and language development, leisure activities, delinquency and substance abuse, friends' activities, and self-perception, attitudes, and values. Caregivers were also interviewed and questions focused on family structure, parent characteristics, parent-child relationships, parent discipline styles, family mental health, and family history of criminal behavior and drug use. Interviews were given in Spanish, English and Polish. Wave 1 also included the Infant Assessment Unit where 412 participants from the longitudinal birth cohort were assessed on each infant's growth and health, cognitive capabilities, and motor skills. Videotaped interactions between these infants and their caregivers are also available. A second wave of data collection with the longitudinal sample was conducted between 1997-1999 with a response rate of 85.94%, and a third wave in 2000-2001 with a response rate of 78.19%.