Early childhood factors found to discriminate between high and low rate offenders are reviewed, including childhood antisocial behavior, parental and sibling criminality, poor supervision, harsh discipline, and parental conflict. Results of a study indicate that peer evaluations of aggressive-withdrawn behavior among female classmates were predictive of later juvenile delinquency. A metanalysis of predictive research indicates that both conduct problems and family conditions are predictive of subsequent delinquency, recidivism, and serious offending. An analysis of criminal careers of Montreal subjects, aged 7 to 25 years, identifies two stages in career development and shows that such careers have a high degree of stability, predictability, and mobility (aggravation of criminal activity). Finally, obstacles to the prediction of dangerousness are examined. Tables, graphs, footnotes and references.