In general, this survey found that youths convicted at the earliest ages (10-12) tended to have the most convictions and the longest criminal careers. The incidence of both official and self-reported offenders tended to peak around age 17. Far more offenses were committed according to self-reports than according to convictions. The summary describes predictors of criminality indicated by the Cambridge Study's results and theories advanced to explain these findings. Reasons for the relative inefficiency of delinquency prediction are discussed, as are methods for identifying the most persistent or chronic offenders at an early age. Other topics covered in the summary include research comparing one-track versus two-track justice for juveniles and the relationship between a biological variable and other nonbiological ones.