Research on traffic offenses committed by prisoners was conducted to identify traffic offense types, factors related to sentences demanded by public prosecutors, and treatment categories for traffic offenders. For 397 prisoners convicted of negligence and causing injury or death, previous criminal history and traffic offense seriousness had a significant effect on sentencing. A survey of 207 parolees and 124 persons under suspended execution of sentence with probationary supervision who committed traffic offenses found that offenders had a history of administrative sanctions for violating traffic laws. Research on the characteristics and treatment of juvenile delinquents adjudicated to training schools showed that the number of delinquents committed to short-term programs in training schools depended heavily on time of admission, area, and sex. Research findings are also reported from studies of classified treatment in probationary supervision, characteristics of asocial juvenile delinquents, and crimes committed by foreigners.