The 1975 data were collected by structured interviews of mothers completed in their homes by lay interviewers. Interviews generally took about one hour.  The T1 (1975) interview of mothers covered a broad range of child health, development, temperament, and problems as well as structural and functional information on the family.  Three coordinated forms of the interview covered the child ages of one year, 2-4 years, and 5-10 years, with the same overall content obtained by inquiries about age-appropriate behaviors.  All data collection, except as noted below, was carried out by in-person interviews by trained interviewers.

The data collection for the follow-up studies should be viewed in the context of the goal of increasing knowledge and understanding of influences on the onset and course of emotional and behavioral disorders in youth in the general population.  Thus, in addition to the diagnostic assessments most of the hypothesized influences or risks were assessed. The basic information from the T1 interview was sought at each of the follow-up interviews of mothers, with parallel questions asked of youth regarding their own behavior in T2 (1983), T3 (1986), and T4 (1992).  The Mother interview also included measures of her own personality and attitudes, additional measures of child rearing and parent-child relationship,  the Diagnostic Interview Schedule for Children (DISC), and service usage.  At T4, when the youth were an average of 22 years old, the DISC was dropped from the mother interview and a history of somatic and psychiatric disturbance for all family members was elicited.  The youth interviews were essentially similar at T2, T3, and T4.  It covered neighborhood and school environment and performance, personality and attitude measures, parenting and parent-child relationship, peer relationships, health, the DISC, and a test of verbal intelligence.  When youth left high school they were also interviewed on their residential, social, romantic, and work settings and status.  In all assessments data on youth drug use and abuse was collected.

At the time of the T3 assessments an additional assessment of 180 adolescent siblings of study youth were completed with the full protocol administered to youth and to the mothers.

Data collection when the sample was in their late 20's had three major components.  First, another in-person interview was completed on the full sample of youth, including parts of the CIDI diagnostic interview.  Second, 240 members of the sample were selected for detailed narrative interviews (see the Transition study, below). Third, a questionnaire covering aspects of adult roles and of recent problem behavior was administered.  In addition, arrest records were collected from the FBI and from New York State, with permission from sample members.

A sixth wave of in-person interviews of this cohort, now in their early 30's began in 2001 and was completed in 2005.  This protocol covers many of the variables in earlier interviews and features SCID screens for Axis 1 and Axis II psychiatric disorders, followed up by clinical interviews. 

A seventh wave of interviews, primarily by mail or on the internet began in 2006. For the first time we are collecting saliva samples for DNA analysis along with most of the items included in previous waves.