THE FINDINGS AND CONCLUSIONS IN THIS STUDY ARE BASED ON DATA DERIVED FROM A SELECTED STRATIFIED RANDOM SAMPLE OF 250 ADULT FORMER PROBATIONERS, WHO HAD BEEN SUPERVISED BY THE NASSAU COUNTY, N.Y., PROBATION DEPARTMENT OUT OF A TOTAL OF 1,250 DISCHARGED IN 1973. THE OVERALL EFFECTIVENESS OF THE PROGRAM WAS DETERMINED BY BOTH THE TYPE OF DISCHARGES (IMPROVED, UNIMPROVED, COMMITTED) RECEIVED BY THE FORMER PROBATIONERS AND THEIR RATES OF RECIDIVISM (ONE OR MORE ARRESTS FOR NEW OFFENSES) DURING THE FOLLOWUP PERIOD. THE FINDINGS AND CONCLUSIONS ARE SUPPORTED BY TABULAR ANALYSES, RECIDIVISM ARREST RATES, AND STATISTICAL TESTS, INCLUDING THE CHI-SQUARE TEST OF INDEPENDENCE AND THE CONTINGENCY COEFFICIENT OF CORRELATION. THESE TESTS WERE USED TO DETERMINE THE PROBABILITY OF AN ASSOCIATION, OR THE EXISTENCE OF A RELATIONSHIP, AND THE STRENGTH OF THIS RELATIONSHIP, IF ANY, BETWEEN ADJUSTMENT ON PROBATION, POSTPROBATION OUTCOME, AND OTHER SELECTED VARIABLES. THE RESULTS GENERALLY INDICATE THAT THE PROBATION SUPERVISION PROGRAM IS AN EFFECTIVE ONE AND THE MAJORITY OF PROBATIONERS SUCCESSFULLY COMPLETE PROBATION AND, BASED ON THE AVAILABLE EVIDENCE, MAKE A FAVORABLE ADJUSTMENT SUBSEQUENT TO DISCHARGE BY CONFORMING TO LAW-ABIDING BEHAVIOR. PROBATIONERS' ADJUSTMENT IN SUPERVISION, AS INDICATED BY THE TYPE OF DISCHARGE RECEIVED, IS SIGNIFICANTLY RELATED TO PREVIOUS ARREST RECORD, RACE, TYPE OF CRIME, AND POSTPROBATION OUTCOME. POSTPROBATION OUTCOME IS INDICATED TO BE SIGNIFICANTLY RELATED TO THE ARREST RECORD PRIOR TO THE OFFENSE FOR WHICH THE OFFENDER WAS PLACED ON PROBATION, ADJUSTMENT ON PROBATION AND, FOR WHITES ONLY, THE TYPE OF SUPERVISION RECEIVED (REGULAR OR DRUG UNIT). TABLES OF DATA ARE INCLUDED AND THE APPENDIXES SHOW THE RELATIONSHIP BETWEEN POSTPROBATION OUTCOME AND SELECTED VARIABLES AS WELL AS THE RELATIONSHIP BETWEEN ADJUSTMENT PROBATION AND SELECTED VARIABLES. (RCB)