AS THE LARGEST WEST GERMAN MODEL INSTITUTION, THE ADULT CORRECTIONAL FACILITY TEGEL HAS A TREATMENT CAPACITY OF 230 CLIENTS AND USES THREE DIFFERENT TREATMENT MODELS: SOCIAL THERAPY (INDIVIDUAL AND GROUP THERAPY OF DIFFERENT PSYCHOLOGICAL ORIENTATIONS), EDUCATION (THE OPPORTUNITY TO COMPLETE HIGH SCHOOL OR JUNIOR HIGH SCHOOL), AND SOCIAL TRAINING (GROUP THERAPY FOCUSING ON SPECIFIC PROBLEMS LIKE ALCOHOLISM AND DRUG ADDICTION, PARTNER RELATIONS, OR LEISURE ACTIVITIES). THE STUDY COMPARED THE RECIDIVISM RATES OF 323 CLIENTS RELEASED FROM THE SOCIAL THERAPEUTIC INSTITUTION TO THOSE OF 889 INMATES RELEASED FROM AN ORDINARY CORRECTIONAL INSTITUTION OVER A STUDY PERIOD OF 3.5 TO 6 YEARS. THE STATISTICAL ANALYSIS INDICATES THAT THE RECIDIVISM RATE OF ALL TREATED PRISONERS, 35.9 PERCENT, WAS SIGNIFICANTLY BELOW THE 59.1 PERCENT OF PRISONERS HAVING RECEIVED NO TREATMENT. FURTHERMORE, THE OFFENSES COMMITTED BY RECIDIVISTS FROM THE SOCIAL THERAPEUTIC INSTITUTION WERE FEWER AND LESS SERIOUS; THE PERIOD BETWEEN RELEASE AND RECIDIVIST OFFENSE WAS LONGER FOR TREATED IMMATES. THE RESULTS ARE SIGNIFICANT AND CANNOT BE EXPLAINED ONLY BY DIFFERENCES IN SELECTION (THE OFFENDERS RECEIVING TREATMENT HAD MORE FAVORABLE PREDICTIONS FROM THE START) AND VARIANCES IN THE LENGTH OF THE PERIOD STUDIED. THE ONLY EXCEPTION EXISTS WITH REGARD TO SEXUAL OFFENSES: UNTREATED SEXUAL OFFENDERS HAD A HIGHER RECIDIVISM RATE THAN TREATED SEXUAL OFFENDERS BY MERLEY FOUR PERCENT. THE STUDY IS ENCOURAGING IN INDICATING THE SUCCESS OF SOCIAL THERAPEUTIC TREATMENT IN PREVENTING RECIDIVISM, BUT THE REASONS FOR THIS SUCCESS ARE STILL UNCLEAR AND WILL BE THE SUBJECT OF ANOTHER PHASE OF THIS STUDY. THE ARTICLE INCLUDES A BIBLIOGRAPHY AND NUMEROUS STATISTICAL CHARTS. -- IN GERMAN.