The Cambridge Study in Delinquent Development is a prospective longitudinal survey of the development of offending and antisocial behavior in 411 London males. At the time they were first contacted in 1961-62, these males were all living in a working-class inner-city area of South London. In addition to interviews and tests with the males, interviews with their parents were conducted by female social workers who visited their homes. These were conducted approximately once a year from when the boy was 8 years old until he was between 14 and 15 years old and was in his last year of compulsory education. The primary informant was the mother. Findings show that a convicted parent, daring, unpopularity, poor housing, and poor child-rearing were the most important independent predictors of occasional offending versus non-offending. Low family income, low social class, poor concentration/restlessness, psychomotor impulsivity, a delinquent sibling, and a father who did not join in the boy's leisure activities were the most important independent predictors of persistent versus occasional offending. There was no overlap between the most important independent predictors of occasional offenders (versus non-offenders) and persistent offenders (versus occasional offenders). 3 tables and 30 references