Delinquent Development, the Cambridge Study

Methods

The Cambridge Study has followed 411 South London males from age 8 to age 48. These males were originally assessed in 1961–1962, when they were in the second forms of six state primary schools and were aged 8 to 9 (West, 1969). Hence the most common year of birth of the males is 1953. The males are not a sample drawn systematically from a population, but rather are the complete population of boys of that age in those schools at that time. The vast majority of boys were living in two-parent families, had fathers in manual jobs, and were White and of British origin.

The study males were interviewed and assessed eight times between age 8 and age 32, and are currently being interviewed at age 46–48. We have been very successful in keeping in contact with them; for example, 95% of those still alive were interviewed at age 18, and 94% at age 32. Currently, 91% of the 394 men still alive have been interviewed at age 46–48. The assessments in schools measured such factors as intelligence, personality, and impulsiveness, while information was collected in the interviews about such topics as living circumstances, employment histories, relationships with females, leisure activities such as drinking, drug use, and fighting, and of course offending behavior.

We also interviewed their parents about once a year from when the boys were 8 until when they were 15. The parents provided details about such matters as family income, family composition, their employment histories, their child-rearing practices (including discipline and supervision), and the boy's temporary or permanent separations from them. Also, the boys' teachers completed questionnaires when the boys were aged about 8, 10, 12, and 14. These furnished information about such topics as their restlessness or poor concentration, truancy, school attainment, and disruptive behavior in class. We also searched the criminal records of the males, of their biological relatives (fathers, mothers, brothers, and sisters), of their wives and cohabitees, and of any person who ever offended with any of our males. The latest searches were in 1994, when most of the males were aged 40.

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