TRENDS IN ALL INDUSTRIAL STATES INDICATE A FURTHER INCREASE OF CRIMINALITY AND ITS CONTINUING SHIFT TOWARD THE YOUNGER AGE GROUPS, BUT THE CENTRAL QUESTION OF WHETHER IMPRISONMENT OR PROBATION AFFECTS THIS GROWTH REMAINS UNDECIDED. MEASUREMENT OF PROBATION'S SUCCESS DEPENDS ON THE NUMBER OF OFFENDERS WHO HAVE NOT REVERTED TO CRIME 5 YEARS AFTER TERMINATION OF PROBATION. UNFORTUNATELY, THE OFFICIAL DATA USED IN THE STUDY ARE LIMITED TO THE PERIOD OF PROBATION. FURTHERMORE, NOT ALL TYPES OF CRIMINALS ARE INCLUDED, BECAUSE THE COURTS, NOT PROBATION OFFICERS, DETERMINE WHICH OFFENDERS ARE SUITED FOR PROBATION. THE NUMBER OF POTENTIAL PROBATIONERS VARIES ACCORDING TO THE SERIOUSNESS OF THE CRIME, THE NUMBER OF TOTAL PROSECUTIONS PER CRIME, THE LENGTH OF THE PRISON SENTENCE IMPOSED, AND THE AGE OF THE OFFENDER. CHANGES IN THE LAW INCREASING THE TOTAL NUMBER OF PROBATIONERS HAVE RAISED THE FAILURE RATE, BUT ONLY BECAUSE OF THE INCREASED NUMBER OF HIGH-RISK CASES RELEASED RATHER THAN IMPRISONED. STATISTICS INDICATE, IN FACT, THAT A LARGE NUMBER OF RISK FACTORS GREATLY INCREASE THE CHANCE OF A PROBATIONER'S FAILURE. THE HIGHEST FAILURE RATE IS PREDICTED FOR THE SINGLE, UNDERAGED, MALE ROBBER WITH DIVORCED PARENTS WHO HAS PREVIOUSLY BEEN SENTENCED TO PRISON AND HAS ALREADY BEEN ON PROBATION. IT IS CONCLUDED THAT PROBATION WORKS WELL WHEN THE RISKS ARE RELATIVELY SMALL AND FEW PROBLEMS OF SOCIAL ADJUSTMENT OCCUR. WHETHER THE CHARACTERISTICS OF THE CRIMINAL REMAIN THE SAME REGARDLESS OF THE TREATMENT METHOD, MAKING FAILURE INEVITABLE, OR WHETHER A CONTROL STYLE COMMON TO ALL AUTHORITIES AFFECTS PROBATION RESULTS MUST BE CLARIFIED BY FURTHER STUDY. TWO TABLES AND NINE REFERENCES ARE SUPPLIED. --IN GERMAN. (INL)