This study reports the results of a longitudinal study of unselected samples of German delinquent children, stratified by frequency of offences recorded before and after the age of criminal responsibility (14 years). A total of 256 young adults (mean age, 22 years), juvenile offenders and control non-offenders, were assessed using the following: a standardized interview regarding family, child development and life history; a multidimensional personality inventory (the Freiburg Personality Inventory, FPI); a version of the Wechsler Adult Intelligence Scale; a self-report questionnaire on the delinquency for which the subject was not apprehended during childhood; and a questionnaire concerning parental child-rearing style. The subsequent criminal records of subjects were followed over the next 20 years. It was possible to define three outcome groups (non-offenders, persisters and desisters), which differed in many respects. The outcome was significantly predicted by several variables. Psychosocial risk variables were the most effective predictors, followed by personality variables and childhood delinquency for which the subject had not been apprehended. The distinction between early-onset and late-onset delinquency as a predictor of adult criminality proved valid only if non-apprehended childhood offending was taken into account. The implications of the study for preventive intervention are discussed.